From space, the earth looks blue. This is about seventy-one percent of its surface is covered by water.
| A．why | B．how | C．because | D． whether |
—Why didn’t you try your best to get on the bus?
—I tried to , but _______ I could, it started moving.
| A．before | B．when | C．until | D．after |
They were walking along the shore _______ a huge wave appeared out of nowhere, sweeping them out to sea.
| A．as | B．while | C．when | D．though |
_______, and the problem will be straightened out.
| A．There being a little effort | B．Having a little effort |
| C．If you have a bit more effort | D．A bit more effort |
He______ on the grass, looking at the clouds in the sky.
| A．is laying | B．has laid | C．was lying | D．has lied |
The country life he was used to _______greatly since 1992.
| A．change | B．has changed | C．changing | D．have changed |