The problem is very difficult. I’m afraid you can’t work it out now.—I fail this time, I will try it again.

Excuse me, is there ________ book by Mo Yan?—Yes. It’s on _________ bookshelf over there.

We think Betty the best student. The sentence structure is ______.

Peter, what have done with the poor dog? He is wet through!—Not ______, mum! I never do the same thing a second time.

There is no doubt ______ everyone will unite and work for better days.