．Never before______ so highly successful in his attempts to forecast the weather accurately on a small scale．
| A．man has been | B．man is | C．has man been | D．will be man |
Although ____ my opinion, the old professor didn’t come up with his own.
| A．against | B．on | C．for | D．in |
The field research will take Joan and Paul about five months;it will be a long time_____we meet them again.
| A．after | B．before | C．since | D．when |
My parents live in a small village. They always keep candles in the house ___ there is a power cut.
| A．if | B．unless | C．in case | D．so that |
It is difficult for us to learn a lesson in life _____we’ve actually had that lesson.
| A．until | B．after | C．since | D．when |
____fire, all exits must be kept clear.
| A．In place of | B．Instead of | C．In case of | D．In spite of |