题目内容：

call for ,call on 都有要求的意思,那么下面这题为什么只选call for?
A man without patience is unfit for the work because it____patience and carefulness.
A calls on B calls for C calls up D calls back

优质解答

call for 意思是“要求,需要”,相当于“need”而call on 通常构成call on sb. to do sth.要求或号召某人做某事