•The baby was crawling around on its hands and knees.婴儿用手和膝盖着地爬来爬去。

•He got/went down on his knees (= got into a position where his knees were on the ground) in front of the altar.他在圣坛前跪下。

•She took the child and sat it on her knee (= on the part of the leg above the knee when sitting down).她抱起孩子放在自己的膝盖上。

•She was wearing an old pair of trousers with rips at the knees.她穿的那条旧裤子，膝盖处破了。

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•The strikes had brought the economy to its knees.罢工使经济严重受挫。

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•She kneed him in the groin.她用膝盖猛撞他的下身。