1. 膝；膝盖；膝关节
    Your knee is the place where your leg bends.

    e.g. He will receive physiotherapy on his damaged left knee.
           因左膝受伤，他将接受物理治疗。
    e.g. ...a knee injury.
           膝关节受伤

2. （坐下时）大腿朝上的面
    If something or someone is on your knee or on your knees, they are resting or sitting on the upper part of your legs when you are sitting down.

    e.g. He sat with the package on his knees...
           他坐着，将包裹放在腿上。
    e.g. I sat in the back of the taxi with my son on my knee.
           我坐在出租车后排座上，儿子坐在我腿上。

3. （裤子的）膝部
    The knee on a piece of clothing is the part that covers your knee.

    e.g. ...jeans with holes at both knees.
           两个膝部都有洞的牛仔裤

4. 膝部
    If you are on your knees, your legs are bent and your knees are on the ground.

    e.g. She fell to the ground on her knees and prayed...
           她跪下祈祷。
    e.g. She was on her knees in the kitchen.
           她在厨房跪着。

5. 用膝盖顶
    If you knee someone, you hit them using your knee.

    e.g. Ian kneed him in the groin.
           伊恩用膝盖顶他的下身。

6. 摧毁；使瘫痪
    If a country or organization is brought to its knees, it is almost completely destroyed by someone or something.

    e.g. The country was being brought to its knees by the loss of 2.4 million manufacturing jobs...
           该国因制造业丧失了240万个就业机会而遭到严重打击。
    e.g. Our aim is to bring this government to its knees, to force it to the negotiating table.
           我们的目标是使该政府屈服，迫使它走上谈判桌。