Do you know Lucy well- Of course I do. We’ve been good friends_______ ten years ago.

I don’t think it is _____ useless competition, because it has offered us ____valuable experience for the next competition.

Who, _____ is the most popular teacher in our school—I think it’s Mr．Zhang.

We left Xi’ an _.___ a very hot summer afternoon

We all know that, ________,the situation will get worse[ ]