Question

一道英语单选题（要详细解析，谢谢!）

5. The question has not been settled so far ________ it is necessary for him to sign up
for a language course in his spare time.
A. whether B. what C. that D. when

Answer 1

选A，首先可以排除B和C；when it is necessary for him to sign up for a language course in his spare time. 如果选D的话，整句意思为：什么时候他有必要参加一个业余时间的语言课程，这个问题到现在还没有解决。虽然在语法上没有问题，但在句意及逻辑上不通顺，所以选A.
请参考！

Answer 2

Youth is not a time of life