——Excuse me, Professor Smith, I was wondering if I could leave a quarter earlier today.
——____.
| A．Nothing the matter. | B．Sure, go ahead | C．Oh, why not? | D．No trouble at all |
The country life he was used to _______greatly since 1992.
| A．change | B．has changed | C．changing | D．have changed |
Most birds find it safe to sleep in the trees, but _______they have eggs or young chicks, they don’t use a nest.
| A．why | B．how | C．unless | D．where |
_______ boys and girls in that school are almost equal.
| A．A number of | B．The numbers of | C．Numbers of | D．The number of |
Every possible means ______to prevent the air pollution, but the sky is still not clear.
| A．is used | B．are used | C．have been used | D．has been used |
It’s already 10 o’clock. I wonder how it_______ that she was two hours late on such a short trip.
| A．came over | B．came about | C．came out | D．came up |