Their vs. There vs. They're: 有什么区别？

• Core Rule: Their must always be followed by a noun (or a noun phrase). It answers the question, Whose?

• The committee members cast their votes. (Whose votes? Theirs.)
• The dogs chased their tails. (Whose tails? Theirs.)
• I appreciate their contribution to the project. (Whose contribution? Theirs.)

• Singular Unknown Gender:

  Someone left their umbrella behind.

  (We don't know if the person was male or female.)
• Singular Non-Binary Gender:

  Alex said their flight was delayed.

  (Alex identifies as non-binary and uses they/their pronouns.)
• Generalizing Rule:

  Every student should bring their ID card to the exam.

  (Refers to each individual student.)

• Function A: There as an Adverb of Place

• We can stop for lunch there.
• Please put the boxes over there, next to the window.
• I've always wanted to visit Paris. I hope to go there next year.

• Function B: There as an Existential Pronoun

• There is a direct flight to Frankfurt. (The subject is a direct flight.)
• There are several issues we need to discuss. (The subject is several issues.)

• The Substitution Test: This is the most powerful tool for verification. If you cannot replace the word with they are and have the sentence remain grammatically correct, they're is the wrong word.

• Correct: "They're building a new hospital." ->

  They are building a new hospital.

  (The sentence works perfectly.)
• Correct: "I was told they're experts in this field." ->

  I was told they are experts in this field.

  (The sentence works perfectly.)

• Incorrect: "The children miss they're friends."
• Substitution Test:

  The children miss they are friends.

  (This is grammatically nonsensical.)
• Analysis: The sentence requires a possessive determiner to modify friends. The correct word is their.
• Correction:

  The children miss their friends.

Use a three-step process. First, check for they're: read the sentence and substitute they are. If it makes sense, they're is correct. If not, proceed to step two. Ask if the word indicates a location (answers Where?) or existence (uses the There is/are structure). If so, use there. Finally, if the word shows ownership (answers Whose?) and is followed by a noun, use their.

Yes, absolutely. The grammar is consistent. When they is used to refer to a single person (for non-binary identity or unknown gender), the possessive form is their and the contraction is they're. For example: "The new manager starts today. I hope they're nice. I need to show them where their office is."

This depends on your institution and professor. Generally, contractions are widely accepted in modern humanities and social science essays to create a more direct and readable tone. However, in highly formal scientific papers, legal documents, or dissertations, it is often recommended to write out the full words (they are) for a more conservative and formal register. When in doubt, ask your professor or consult your university's style guide.

This is a very common problem. The best defense is active proofreading. Intentionally slow down when you type one of these words. Another effective technique is to read your message or text aloud before sending it. Your ear can often catch an error that your eye, moving quickly, might miss. For example, reading

I am going to they are house

Focus on their unique letters. There has here inside it, linking it firmly to location. Their has an i in it; you can imagine the i as a person, and people own things. This simple association—here for place, i for person/possession—can be a very effective mental hook.

There're is a contraction of there are. You will hear it in rapid, informal speech ("There're cookies in the kitchen"). However, it is extremely rare in writing and is often considered awkward or incorrect in almost all written contexts, including informal ones like texting. As a learner, your best practice is to always write there are in full. This will always be correct and clear.