问题补充:
Many teenagers say that they have a lot of friends, they really have no best friend.
A. when
B. while
C. if
D. because
答案:
A. when
(答案→)B. while
C. if
D. because
解析:考查从句连词的选择。句意为很多年轻人说尽管他们有很多朋友,但是他们实际上没有最好的朋友。While 意为尽管 when既然,当……时候 if如果 because 因为