There arepeople in the supermarket. It’s so crowded.

Waste paper is collected ______ recycling. [ ]

Tommy, do you know if Frank _____ to the theatre with us this Sunday if it _____?—Sorry, I have no idea.

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

So far we have done a lot to build a low-carbon economy, yet it is still _________ ideal. We have to work even harder.