The reason _______ he gives for not coming is that his mother is ill.
| A．for which | B．which | C．why | D．about which |
----Iam sorry to have ____ too much of your time.
----That's OK, and I am glad to help you.
| A．taken up | B．taken on | C．taken off | D．taken in |
Mary and her friends paid_____visit to _______Summer Palace yesterday.
| A．the; / | B．a; the | C．a; / | D．the; a |
It was back home after the experiment.
| A．not until midnight did he go | B．until midnight that he didn’t go |
| C．not until midnight that he went | D．until midnight when he didn’t go |
is believed that improvement in health care will lead to a stronger , more prosperous economy .
| A．As | B．That | C．This | D．It |
----May I smoke here ?
-----If you , choose a seat in the smoking section .
| A．should | B．could | C．may | D．must |