I've known somebody/something to do something or somebody/something has been known to do somethingSOMETIMES used to say that someone does something sometimes or that something happens sometimes, even if it is unusual 我知道某人做过某事/发生了某种情况〔尽管并不常见〕 People have been known to drive 500 miles just to visit the shop. 有人驾车500英里只是为了去这家商店。
This type of fish has been known to live for 10 years or more. 这种鱼有活10年甚至更久的。
→ I’ve known somebody/something to do something at know1(9)