The potato is a plant ____ in places ____ it is too cold to grow some other plants.
| A．grown; where | B．to grow; that | C．growing; where | D．grown; that |
---Tell us, Mark, what is the cause of the American Civil War?
---Well, is it _______the black slaves wanted freedom?
| A．how | B．why |
| C．because | D．when |
--- I can’t carry the luggage. It’s so heavy.
--- Why not have someone strong enough_______ you a hand then?
| A．give | B．to give |
| C．giving | D．to have given |
Although she brushed the old pot_______, she could not make it completely clean, which made her very upset.
| A．roughly | B．thoroughly |
| C．instantly | D．occasionally |
Mr. Smith is always on time for everything. How ____ it be that he was late for the important meeting?
| A．should | B．can |
| C．may | D．must |
---Your grandfather still seems very energetic, although he is already in his seventies now.
---Yes, he _______in the army for three years when he was young.
| A．would serve | B．served |
| C．had served | D．has served |