问题
选择题
.______ he can finish his task on time is of great importance.
A.Whenever
B.If
C.Whether
D.Whichever
答案
答案:C
题目分析:本题考查主语从句。B项if作为“是否”讲只能引导动词之后的宾语从句,因而排除;A,D两项与题意不合。如选A项,原题可改为“…is of no importance”。故答案为C.