______ the students who took part in the training is 450.
| A．A number of | B．A lot of | C．Lots of | D．The number of |
Not until I completed the form that half questions were not relevant to me.
| A．had I realized | B．I had realized |
| C．I realized | D．did I realize |
about this computer program, a huge amount of time and energy .
| A．Should I know; be saved |
| B．If I had known; can be saved |
| C．Had I known; would have been saved |
| D．Did I know; was saved |
Hearing the bell ringing, out .
| A．rushing the children | B．rushed the children |
| C．were rushing the children | D．the children rushed |
—Can I smoke here?
—No, at no time in the library.
| A．permits smoking |
| B．does smoking permit |
| C．smoking is permitted |
| D．is smoking permitted |
So far, what we have done is destroying the earth; only by changing we live we save it.
| A．that; will | B．how; can |
| C．what; do | D．which; shall |