问题

It is uncertain _______ side effect the medicine will bring about,although about two thousand patients have taken it

A:that
B:what
C:how
D:whether

正确答案是：

同类题型

I once lived in a house _______ roof hasfallen in.

His brother won’t go to play basketball until his work.

Not until he called the secretary three times _________ that the manager went to an important meeting.

that’s enough. ________ price will be beyond my reach.

_____more countries can use natural energy in the future remains to be seen