共同地

§ Don't confuse 共同地 with 共同

Many learners get confused between 共同地 (gòngtóngde) and 共同 (gòngtóng). While they both relate to the idea of 'common' or 'joint,' their grammatical functions are different. 共同地 is an adverb, meaning it modifies verbs or adjectives. It tells you *how* something is done – jointly or in common. 共同, on the other hand, can function as an adjective (common, joint) or sometimes a noun (common ground/points). Think of 共同地 as adding the '-ly' to 'common' in English, making it 'commonly' or 'jointly.'

DEFINITION

共同地 (gòngtóngde): adverb, jointly; in common.

DEFINITION

共同 (gòngtóng): adjective/noun, common; joint.

Let's look at an example to make this super clear:

Here, 共同地 modifies the verb 完成 (wánchéng, to complete), telling us *how* the project was completed. If you said “我们共同完成了这个项目,” it would also be correct, but 共同 here functions as an adverbial, implying 'jointly.' Adding '地' explicitly marks it as an adverb.

In this sentence, 共同 acts as an adjective modifying 兴趣 (xìngqù, interests). You absolutely cannot use 共同地 here because 'jointly interests' doesn't make sense. Adverbs don't modify nouns.

§ Overusing 共同地 in places where 共同 is more natural

Sometimes learners overuse 共同地 when 共同 would be more idiomatic or natural, even if both are technically grammatically acceptable. This often happens when 共同 functions as an adverbial without the '地' suffix, which is common in Chinese for certain adverbs.

While “他们共同地生活了十年” is not strictly incorrect, the version without '地' sounds more fluent and natural to native speakers. This is because 共同 here is already acting adverbially. The '地' particle makes the adverbial explicit, but it's not always necessary, especially with two-character adverbs like 共同.

§ Using 共同地 when a different adverb is needed

Make sure 共同地 actually conveys the meaning of 'jointly' or 'in common.' Sometimes, learners might use it when other adverbs like 'together' (一起 yīqǐ) or 'unanimously' (一致地 yīzhìde) would be more appropriate, depending on the nuance.

• If you mean 'together' in a simple sense of doing something physically in the same place, 一起 (yīqǐ) is usually better.

  我们一起去图书馆。(Wǒmen yīqǐ qù túshūguǎn.)
  We go to the library together.

  Using “我们共同地去图书馆” would sound a bit odd here, as it emphasizes the 'joint' nature of the action rather than simply going 'together.'

• If you mean 'unanimously' or 'with one accord,' then 一致地 (yīzhìde) is a better choice.

  大家一致地同意这个计划。(Dàjiā yīzhìde tóngyì zhège jìhuà.)
  Everyone unanimously agreed to this plan.

  Here, 共同地 would imply they agreed 'in common,' which is close, but 一致地 captures the 'unanimous' aspect more precisely.

§ Forgetting the '地' for adverbial use

While we just discussed when 共同 can stand alone as an adverbial, there are many cases where 共同地 is explicitly needed, especially with verbs that require a clear adverbial modification. Omitting '地' in these situations can make your sentence sound incomplete or grammatically awkward.

In this case, 共同地 clearly modifies 承担 (chéngdān, to bear/undertake). Just saying “他们共同承担了责任” is also acceptable, but “共同地” emphasizes the adverbial function more strongly, especially for learners. It's often safer to include '地' when you intend an adverbial meaning, unless you are confident that the '地' is naturally omitted in that specific context.