问题
选择题
As a saying goes, the wise man knows he knows nothing, _________ the fool thinks he knows all.
A．when
B．while
C．as
D．though
答案
答案：B
题目分析：考查连词：A. when当…时候，B. while当,..时候，虽然，然而，C. as 因为，随着，正如，D. though虽然，句意：俗话说，明者知自之不知，愚者自认无所不知。这里while表示对比，选B。