Scientists say it will be five or six years ________ it is possible to test this medicine on humans．
| A．after | B．before | C．since | D．When |
Why didn't you tell me there was no meeting today? I _____ all the way here _____the heavy snow.
| A．needn't have driven；through | B．can't have driven；across |
| C．mustn't have driven；through | D．shouldn't have driven；cross |
Never _______ forget the days when _______ together with you．
| A．shall I；I lived | B．shall I；did I live |
| C．I shall；I lived | D．I shall；did I live |
The two old sisters，_______ so long，held each other and burst into tears．
| A．being separated | B．having been separated |
| C．having separated | D．had been separated |
— When will you leave for Paris for a visit?
—_____next month.
| A．Until | B．After | C．At | D．In |
In such dry weather the flowers will have to be watered if they _____.
| A．have survived | B．would survive | C．are to survive | D．will survive |