The chairman ________ hold office for five years according to the constitution.
| A．might | B．could |
| C．need | D．shall |
He is rather difficult to make friends with, but his friendship, ________, is more true than any other.
| A．after gaining | B．while gaining |
| C．once to gain | D．once gained |
Many people can’t learn any lessons from the mistakes they’ve made __________ they get hurt somehow.
| A．whether | B．unless | C．if | D．as |
---- They like going to sleep early, don’t they?
---- Yes. They are accustomed ___________ very late.
| A．to stay up | B．to not stay up |
| C．to staying up | D．to not staying up |
— Believe it or not, my sister and I are twins.
— Oh, you must have had the case _________ you were taken for your sister.
| A．which | B．whose | C．where | D．when |
Last year the number of students who graduated with a driving license reached 200,000, a(n) ________ of 40,000 per year.
| A．amount of | B．quantity |
| C．average | D．number |