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B1 — Rules, Advice, and Instructions

B1 · Intermediate Chapter 13

Rules, Advice, and Instructions

Q: What is the difference between 'should' and 'ought to'?

They mean the same thing, but `ought to` is more formal and requires 'to'. `Should` is much more common in daily speech.

Q: Can I use 'must' for the past?

No, for past obligation use `had to`. For past deduction, use `must have` + past participle.

Q: What is the difference between 'mustn't' and 'can't'?

Both show prohibition, but `mustn't` is usually about rules, while `can't` is about lack of ability or general impossibility.

Q: Can I use 'can' instead of 'should'?

Yes, but it changes the meaning. `Should` is for advice (what is good), while `can` is for possibility (what is possible).

4 Total Rules

48 examples

6 min

Rules in This Chapter Quick Practice

Chapter in 30 Seconds

Master the art of giving helpful advice and clear instructions with confidence.

Suggest better choices using the modal verb should.
Express non-negotiable rules and necessities using must.
Link specific conditions to advice and direct commands.

Command the room and guide others with precision.

What You'll Learn

Feeling ready to give advice and strong instructions like a pro? This chapter will show you how to use if with commands and express what must be done, helping you guide others clearly and effectively in everyday conversations.

Giving Advice and Recommendations (Should)
Should is your go-to modal verb for giving friendly advice and expressing what's a good idea.
Must: Strong Obligation & Necessity
Must conveys undeniable obligation or necessity, making your statements clear and impactful.
First Conditional for Advice (should)
Offer clear, helpful advice for future scenarios using if + present, should.
First Conditional: Commands & Advice (If + Imperative)
Give clear, conditional instructions or advice with If + Present Simple, Imperative.

Learning Objectives

By the end of this chapter, you will be able to:

1
By the end you will be able to offer polite recommendations for common problems using should.
2
By the end you will be able to state firm legal or personal requirements using must.
3
By the end you will be able to construct complex conditional sentences to give advice based on specific situations.

Chapter Guide

Overview

As you continue your journey in B1 English grammar, you’re building the skills to connect with people and express yourself clearly in a wide range of situations. This chapter is all about giving effective English rules, advice, and instructions. Imagine being able to help a friend, offer clear guidance, or explain important steps without sounding aggressive or unclear. That's exactly what you'll learn here!

We'll dive into the subtle art of using words like should to offer helpful recommendations, like "You should try that new cafe." You'll also master must for those times when something is truly essential, as in "You must submit your report by Friday." We’ll also explore how to combine these with the first conditional – using "if" clauses to give advice and commands that are relevant to specific situations, such as "If you want to pass the exam, you should study every day" or "If you see a problem, tell your manager immediately." By the end, you'll be confidently guiding others and understanding important directions like a native speaker.

How This Grammar Works

Learning to give and understand rules, advice, and instructions effectively makes your English sound much more natural and confident. Let's explore how these pieces fit together, moving from gentle suggestions to strong directives.

First, for friendly advice and recommendations, we use should. This is your go-to for suggesting the best course of action without being too strong or bossy. For example, "You should drink more water" or "They should call their parents more often." It implies a good idea, but the choice is still up to the listener.

When something is absolutely essential, a strong obligation, or a logical necessity, we use must. This isn't a suggestion; it's a rule, a requirement, or something that is highly certain. Think of signs like "All visitors must check in at reception" or personal vows like "I must finish this project tonight." If there’s no other option, or the consequences of not doing it are serious, must is the word.

Now, let's add a condition! The first conditional for advice (should) combines a possible future situation with advice. The structure is simple: If + present simple, should + base verb. This allows you to give advice that is specific and relevant to a particular scenario. For instance, "If you feel tired, you should take a break" or "If it rains tomorrow, we should bring umbrellas." This makes your advice more practical and targeted.

Finally, we have the first conditional for commands & advice (If + Imperative). Here, instead of using should, you give a direct command or instruction in the second part of the sentence. The structure is: If + present simple, imperative (base verb form). For example, "If you arrive late, wait outside" or "If you have any questions, ask the teacher." This is perfect for giving clear, actionable instructions based on a potential future event. These structures together give you a powerful toolkit for guiding conversations and ensuring clarity in your interactions.

Common Mistakes

It's easy to mix up these useful phrases. Here are some common pitfalls and how to avoid them:

1✗ Wrong: You must try the new coffee shop. (Sounds too strong, like an order)

✓ Correct: You should try the new coffee shop. (A friendly recommendation)

*Explanation:* Use should for suggestions, not must, which implies a necessity or obligation.

1✗ Wrong: If you want to lose weight, you must to exercise. (Incorrect grammar with "to")

✓ Correct: If you want to lose weight, you must exercise. (Correct verb form)

*Explanation:* After modal verbs like must or should, always use the base form of the verb without "to."

1✗ Wrong: If it rains, you should to take an umbrella. (Incorrect grammar with "to")

✓ Correct: If it rains, you should take an umbrella. (Correct verb form)

*Explanation:* Like with must, should is followed directly by the base verb form.

Real Conversations

Here’s how these grammar points appear in everyday chats:

"I'm really struggling with my English homework. It's so difficult!"

"Oh, really? If you're having trouble, you should ask the teacher for help during office hours. She's very approachable."

"My flight leaves at 6 AM tomorrow. I'm worried I'll miss it."

"Wow, that's early! You must set several alarms, and you should pack your bag tonight so you don't forget anything important."

"I'm going hiking this weekend, but the weather forecast looks a bit unpredictable."

"If the weather changes suddenly, make sure you have a map and a fully charged phone. And if it starts raining heavily, turn back immediately!"

Quick FAQ

When should I use "should" versus "must" for advice?

Use "should" for advice, recommendations, or what's generally a good idea. It's a suggestion. Use "must" when there's a strong obligation, a rule, a necessity, or a strong personal conviction. It implies no real choice.

Can I use "if" with "must"?

While grammatically possible (e.g., "If you must leave, please close the door"), it's less common for *giving advice*. It usually expresses a resignation or necessity already acknowledged. For conditional advice, stick to "should" or an imperative.

Is "you should" always polite?

Generally, yes, "you should" is polite. However, if used too frequently or with a lecturing tone, it can sometimes sound a little preachy. To soften it further, you can say "I think you should..." or "Perhaps you should..."

What's the difference between "If you want to..." and "If you need to..." when giving advice?

"If you want to..." implies a personal desire or goal (e.g., "If you want to improve, you should practice daily"). "If you need to..." implies a requirement or necessity (e.g., "If you need to contact me, call this number"). Both are useful in conditional advice.

Cultural Context

In English, the way we give advice and instructions often reflects politeness and directness. While must clearly states an obligation, it can sometimes sound very direct, almost like an order, especially in informal contexts. Native speakers often prefer should or softer phrases (like "You might want to..." or "I suggest you...") even for important advice, to maintain a friendly tone. Using the first conditional with an imperative ("If you're cold, put on a jacket") is common and generally accepted as clear and direct, but still contextual. Understanding these nuances helps you sound more natural and avoid accidental rudeness.

Key Examples (8)

You `should really try` the new coffee shop downtown; their lattes are amazing.

Giving Advice and Recommendations (Should)

I think we `should start` our project early to avoid any last-minute stress.

Giving Advice and Recommendations (Should)

You **must** hand in your assignment by Friday.

Must: Strong Obligation & Necessity

I **must** remember to call my parents tonight.

Must: Strong Obligation & Necessity

`If you're hungry, you should grab a snack.`

First Conditional for Advice (should)

`If it rains later, you should take an umbrella with you.`

First Conditional for Advice (should)

`If you feel cold, close the window.`

First Conditional: Commands & Advice (If + Imperative)

`If you're hungry, grab a snack from the fridge.`

First Conditional: Commands & Advice (If + Imperative)

Tips & Tricks (4)

💡

Soften your advice

Start with 'I think...' or 'Maybe you should...' to sound less bossy and more like a friend.

frontend.learn_grammar.from_rule: Giving Advice and Recommendations (Should)

💡

The 'To' Rule

Always remember: Must + Verb. Never Must + To + Verb. It's the #1 mistake teachers see!

frontend.learn_grammar.from_rule: Must: Strong Obligation & Necessity

💡

The Comma Rule

Always remember: If 'If' is first, a comma is a must. If 'If' is in the middle, no comma is needed.

frontend.learn_grammar.from_rule: First Conditional for Advice (should)

🎯

Use 'Please' to Soften

Imperatives can sound rude. Always add 'please' or 'just' if you are talking to a peer or superior. 'If you have time, please help me' sounds much better than 'If you have time, help me.'

frontend.learn_grammar.from_rule: First Conditional: Commands & Advice (If + Imperative)

Key Vocabulary (6)

recommend to suggest something as a good choice mandatory required by law or rules passenger a person traveling in a vehicle instruction detailed information on how to do something prohibit to formally forbid something advice guidance or recommendations

Real-World Preview

plane

At the Airport Security

stethoscope

A Visit to the Doctor

Review Summary

Subject + should + Verb (base form)
Subject + must + Verb (base form)
If + Present Simple, Subject + should + Verb (base)
If + Present Simple, [Imperative Verb]

Common Mistakes

Modal verbs like 'should' and 'must' are followed directly by the base verb. Never use 'to' after them.

Wrong: You should to study more.

Correct: You should study more.

In conditional advice, the second clause still needs a subject (you, he, she) before the word 'should'.

Wrong: If you are hungry, should eat.

Correct: If you are hungry, you should eat.

In the 'if' clause of a first conditional, we use the Present Simple, not 'will'.

Wrong: If you will see him, tell him the news.

Correct: If you see him, tell him the news.

Rules in This Chapter (4)

Next Steps

You've taken a huge step toward fluency! Being able to guide others is a key leadership skill in any language. Keep practicing these patterns and you'll be a master communicator in no time.

Write 5 rules for your favorite sport using 'must' and 'should'.

Look at a recipe and identify the conditional instructions.

Continue to: Talking About Facts and Constant Truths

Quick Practice (10)

Choose the most natural sentence.

Which sentence is a correct instruction?

✓ Correct! ✗ Not quite. Correct answer: If you are tired, go to bed.

The imperative does not use a subject or 'to'.

frontend.learn_grammar.from_rule: First Conditional: Commands & Advice (If + Imperative)

Find the mistake in the sentence.

Find and fix the mistake:

If you will see him, you should say hello.

✓ Correct! ✗ Not quite. Correct answer: will see

We don't use 'will' in the 'if' clause. It should be 'see'.

frontend.learn_grammar.from_rule: First Conditional for Advice (should)

Complete the sentence with the correct form of the verb in parentheses.

If it ___ (rain), don't forget your umbrella.

✓ Correct! ✗ Not quite. Correct answer: rains

We use the Present Simple in the if-clause.

frontend.learn_grammar.from_rule: First Conditional: Commands & Advice (If + Imperative)

Fill in the blank with 'must' or 'mustn't'.

You ___ touch the paintings in the gallery. It's against the rules.

✓ Correct! ✗ Not quite. Correct answer: mustn't

Touching paintings is forbidden, so we use 'mustn't'.

frontend.learn_grammar.from_rule: Must: Strong Obligation & Necessity

Choose the correct sentence.

Which sentence is grammatically correct?

✓ Correct! ✗ Not quite. Correct answer: He must go home.

Must does not take an 's' and is not followed by 'to'.

frontend.learn_grammar.from_rule: Must: Strong Obligation & Necessity

Correct the error in this sentence: 'I musted work yesterday.'

Find and fix the mistake:

I musted work yesterday.

✓ Correct! ✗ Not quite. Correct answer: I had to work yesterday.

The past tense of 'must' (obligation) is 'had to'.

frontend.learn_grammar.from_rule: Must: Strong Obligation & Necessity

Choose the correct sentence.

Which sentence is correct?

✓ Correct! ✗ Not quite. Correct answer: You should see a doctor.

'Should' is followed by the base verb without 'to'.

frontend.learn_grammar.from_rule: Giving Advice and Recommendations (Should)

Complete the sentence with the correct form of the verb in brackets.

If you ___ (want) to pass the exam, you should study harder.

✓ Correct! ✗ Not quite. Correct answer: want

The 'if' clause uses the Present Simple.

frontend.learn_grammar.from_rule: First Conditional for Advice (should)

Choose the best piece of advice.

If it's raining outside, ___.

✓ Correct! ✗ Not quite. Correct answer: you should take an umbrella

'Should' is followed by the base verb without 'to'.

frontend.learn_grammar.from_rule: First Conditional for Advice (should)

Find the mistake in the sentence.

Find and fix the mistake:

If the phone will ring, answer it immediately.

✓ Correct! ✗ Not quite. Correct answer: will ring

Change 'will ring' to 'rings'.

frontend.learn_grammar.from_rule: First Conditional: Commands & Advice (If + Imperative)

Score: /10

Common Questions (6)

They mean the same thing, but ought to is more formal and requires 'to'. Should is much more common in daily speech.

Yes! You can say 'We should go tomorrow.' It functions as a suggestion for a future action.

No, for past obligation use had to. For past deduction, use must have + past participle.

Both show prohibition, but mustn't is usually about rules, while can't is about lack of ability or general impossibility.

Yes, but it changes the meaning. Should is for advice (what is good), while can is for possibility (what is possible).

In English, the 'if' clause in a first conditional sentence is already understood to be in the future. Using will is redundant and grammatically incorrect.