It remains to be seen he will solve the problem or not.
A. that
B. what
C. which
D. whether
网友回答
A. that
B. what
C. which
D. whether
解析:考察名词性从句。It是形式主语,真正的主语从句是whether he will solve the problem or not。Whether在句中不充当任何成分,指起引导作用,与or not连用。结合句意可知D正确。句意:他是否会解决这个问题有待于进一步观察。