Theskyismuchbluerwehavetakenac-优题课

The sky is much bluer ________ we have taken action to protect the environment．（　　）

A．

because

B．

before

C．

until

D．

unless

科目英语题型选择题难度中等

知识点：连词辨析

This medicine millions of people's lives since it was put into use．（　　）

is saving

will save

has saved

had saved

Last week Vivian a dress for her mother with her first﹣month salary．（　　）

buy

bought

will buy

would buy

A good friend is someone you share your pleasure and pain with．（　　）

ought

need

can

must

The nurse won't leave her patients she's sure they are all taken good care of．（　　）

unless

because

since

The flight was delayed by the storm， the passengers had to wait at the airport．（　　）

but

for