Mike seldom asks ______ questions in class, but today he raised ______ fairly good one．
| A．/; a | B．the; a | C．/; the | D．/; / |
A student at a Nevada middle school opened fire on campus, wounding two l2-year-old boys and__________ a math teacher.
| A．kill | B．killing | C．killed | D．to kill |
It never will rain roses. __________ we want to have more roses. we must plant trees.
| A．When | B．Unless | C．Until | D．While |
I really don’t know _________ I put my wallet after I paid the bill．
| A．where was it | B．it was where that |
| C．where was it that | D．where it was that |
During the examination we are required to stay in our seats, keep our eyes on our work, ____ to anyone.
| A．instead of speaking | B．rather than speak |
| C．and not to speak | D．but would not speak |
________ these experiments were successfully completed would we think of going into humans.
| A．If only | B．Only if | C．So that | D．Even if |