—I am going to America.
—how long you there?
| A．are; stayed | B．are; staying | C．have; stayed | D．did; stay |
We have done things we ought not to have done and ________ undone things we ought to have done.
| A．left | B．leave |
| C．will leave | D．leaving |
Paper produced every year is ________ the world’s production of vehicles.
| A．the three times weight of | B．three times the weight of |
| C．as three times heavy as | D．three times as heavier as |
The two ladies are ________ the same age, but there seems to be ten years ________ them.
| A．at, between | B．about, among |
| C．as, among | D．of, between |
I planned ________ to see you last week, but I was ill.
| A．to have come | B．to come |
C．to be coming | D．to have been coming |
While building a tunnel through the mountain, ________ .
| A．an underground lake was discovered |
| B．there was an underground lake discovered |
| C．a lake was discovered underground |
| D．the workers discovered an underground lake |