_____ is even more important is that as the earth cooled down, water began to appear on its surface.
| A．As | B．That | C．What | D．Where |
Every possible means ____, but none ____ successful．
| A．has tried; has proved | B．tried; proves |
| C．has been tried; proves | D．is being tried; is proved |
.The question he asked is hard ____ ．
| A．for answer | B．to answer | C．to be answered | D．answering |
.By the end of last year, another new gymnasium ____ in Beijing.
| A．would be completed | B．was being completed |
| C．has been complete | D．had been completed |
.More than a dozen students in that school ＿＿＿ abroad to study medicine last year.
| A．sent | B．were sent | C．had sent | D．had been sen t |
.－－Why did you leave that position?
－－ I ＿＿a better position at IBM.
| A．offer | B．offered | C．am offered | D．was offered |