单项选择题
A.consistent B.continual C.continuous D.numerous
The United Nations Conference on Global Environment, w...
单项选择题The United Nations Conference on Global Environment, which took place earlier this year in Vienna, was a very（） meeting.
A.productive B.communicative C.aggressive D.protective
We watched the plane（）behind the clouds.A.disappearingB...
单项选择题We watched the plane（）behind the clouds.
A.disappearing B.disappeared C.diving D.dived
Pipes made of plastic are now widely used in building ...
单项选择题Pipes made of plastic are now widely used in building as they are light and do not become （）in water.
A.ripe B.instant C.rotten D.mature
