Using "lai" as a dummy verb
The verb 来 (lái) can be used as a "dummy verb," similar to the way "do" is used in English. To illustrate the point, imagine a bottle of pickles that you want to open but can't because the lid is so tight. You start passing it around to see who can open it, and no one is able to, until your beefy friend comes in and says, "我来!" He is saying, "Let me do it!"
The structure for using 来 as a dummy verb is very basic. Usually it is a very short phrase, kind of like "your turn!" or "let me give it a shot!" or "you do it!" in English. Usually it is used with 你 or 我 as the subject, and it ends with the 来. Sometimes it can end with a 吧.
(让 +) Subj. + 来
The point of calling 来 a "dummy verb" is that it does't have the original meaning of "to come." It just takes the place of whatever the verb would be in the context.
- 你 来 ！You do it!
- 我 来 吧。Let me do it.
- 让 他 自己 来 。Let him do it himself.
- 还是 你们 自己 来 吧 。It's better that you do it by yourselves.
- 你 写 得 好看 ，你 来 吧 。You write well. You write it.
A few example dialogs to provide clearer context:
- A:谁 能 读 一 下 这 段 话 ？Who can read this passage?
- B:老师 ，我 来 。Teacher, let me read it.
- A:你 怎么 做 得 这么 慢 ？How come you do it so slowly?
- B:你 觉得 我 慢 ？你 来 ！You think I'm slow? You do it!
- A:这个 箱子 真 重 ！This box is so heavy!
- B:我 来 吧 。 Let me help.
Sources and further reading
- 现代汉语形式动词研究 Research on Dummy Verb in Modern Chinese
- 現代漢語中的形式動詞 Dummy Verbs in Contemporary Chinese