when( ) is still unknown to us all A、starting B、start C、going to start D、to start选什么呀

问题描述:

when( ) is still unknown to us all A、starting B、start C、going to start D、to start选什么呀

选D,表示什么时候开始还是未知的
It is still unknown to us all when to start.
放到后面就好理解了.