Exercise is the key ______ your health．

Why do you look sad?— There are so many problems ________. [ ]

Can you come for an interview this Monday —No problem. I’m free ________ an interview _______ any time.

s wondering if you could lend me some moremoney— Sorry, I’ve got _____ at hand myself. You know theMP4 player cost me all I had just now.

Look at the picture . ________ big watermelon it is! —Yes. Let’s see how heavy it is .