问题补充：
One of the most important social problems of today is jobs to the
unemployed.
A. what to be given
B. having given
C. how to give
D. to have given
答案：
A. what to be given
B. having given
(答案→)C. how to give
D. to have given
解析：做表语的非谓语动词表示具体时间（将来）的行为，故用不定式一般时，排除 BD，
短语中不缺少成分，排除A
