please pass the key _______ the lock. —oh! Is it a set _______ keys?[ ]

There’s some litter on the floor. Please ______.

Have you got any news from Jane about the English contest？— No. She said she ______ know when ______ be held, either.

I like watching football games ______ TV. [ ]

The water ______ cool when I jumped into the pool for morning exercise.