There are so many kinds of computers in the shop. I really don’t know ______ to choose.

I was very happy to receive lots of nice presents _____ the morning of Women’s Day. [ ]

May I smoke here，please?—I am afraid you ．This is a non-smoking area．

We have to stay at home instead of going finishing because it is raining ________________.

This sentence is difficult to understand.Can you make of it?