高中英语动词语态单选题

I was out of town at the time, so I don’t know exactly how it _______. 

A．was happening

B．happened

C．happens

D．has happened

The wet weather will continue tomorrow when a cold front ______ to arrive.

A．is expected

B．is expecting

C．expects

D．will be expected

Over the past decades, sea ice     in the Arctic as a result of global warming.

A．had decreased

B．decreased

C．has been decreasing

D．is decreasing

With the help of high technology, more and more new substances ______ in the past years.

A．discovered	B．have discovered
C．had been discovered	D．have been discovered

I got caught in the rain and my suit _______.

A．has ruined	B．had ruined
C．has been ruined	D．had been ruined