Knee
Common expressions
bend your knees
hurt your knee
scrape / graze your knees
get down on your hands and knees
have / need an operation on your knee
(the water) came right up to your knees
Exercise
Common expressions
I hurt my knee quite badly while playing football. The doctors think I may need an operation on it.
Always remember to bend your knees when lifting heavy objects or you’ll hurt your back.
We had to wade across the stream and the water came right up to our knees!
I got down on my hands and knees and looked under the bed for my other sock.
Jamie tripped over a stone which was lying on the pavement and scraped / grazed his knees. His mother had to put a couple of plasters on them when he got home.