Elephants, which are the largest mammals on the earth, have almost no natural enemies ______ human beings.
--- Jack fell off the ladder yesterday, but he is all right now.---What a lucky dog! He _______ himself badly.
---Tell us, Mark, what is the cause of the American Civil War?---Well, is it _______the black slaves wanted freedom?
--- I can’t carry the luggage. It’s so heavy.--- Why not have someone strong enough_______ you a hand then?
Although she brushed the old pot_______, she could not make it completely clean, which made her very upset.
Mr. Smith is always on time for everything. How ____ it be that he was late for the important meeting?