used to do sth
常见例句
- Sth . be used to do sth.
是固定词组，意思是用来做某事。 - Perfomatives: are the sentences that did not state a fact or describe a state, and are not verifiable. But they are used by the speaker to do sth.
既不是陈述事实也不是描写状态，无法证实，但被说话者用来做事的。
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