问题

Most environmental problems exist because______measures for preventing them have not been taken in the past.[ ]

A: accurate
B: extreme
C: tentative
D: adequate

正确答案是：

同类题型

Whose advice doyou think I should take — __________

Not until they left school _________ how much their teachers loved them and helped them.

Can you speak a little louder I can ______ hear you. —OK.

______ the exams to worry about, I have to work really hard this weekend. [ ]

It’s sunny today. How about going riding—________