In order not to be disturbed, I spend three days _______ in my study.
| A．locking | B．locked | C．to lock | D．lock |
—You ought to have called him yesterday．
—Yes，I know I．
| A．ought to | B．have to | C．should have | D．must have |
Persons under 16 not be employed in our country．
| A．shall | B．can | C．may | D．will |
—I’m sorry I have failed again in the math exam．
—？You’ve been working hard at the subject．
| A．How | B．How come | C．Why not | D．When |
Everybody had an impression she was a good match for the young man．
| A．that | B．which | C．with which | D．for which |
So amusedthat I couldn’t help laughing when I saw the performance given by the children．
| A．I felt | B．I feel | C．did I feel | D．had I felt |