问题

He smiled politely ________ Mary apologized for her drunken friends(2012·山东,27)
A:as
B:if
C:unless
D:though
B:if
C:unless
D:though
正确答案是:
同类题型
, I havenever seen anyone who’s as capable as John.
The twin towers fell downIt looked_____ a huge piece of chocolate had been melted down(溶化)
_________ now to protect the environment, we’lllive to regret it.
I’ll always stand by you when you are in need.–It’s nice of you. Your support is really _______ .