问题

I just don’t understand _______ that prevents so many Americans from being as happy as one might expect.

A:why it does
B:what it does
C:what it is
D:why it is;

正确答案是：

同类题型

You can trust him because he always ________.

If you have a toothache, you should go to see a______.

Nowadays ______ Internet is becoming increasinglypopular and ______ new high speed broadband network was recently started.

child is ________, with theirown needs, preferences and talents.

What should we ____________ in class We should pay attention ___________ notes when necessary.