高一英语 名词性从句

Question

It is not clear_____the high price will soon be controlled.
A.if B.whether
为什么选whether，不选if。
引导主语从句不是只有放在句首才不能用if吗？本句没有放在句首啊?

Answer 1

这句话其实是个强调句，完整的应为：
It is not clear that whether the high price will soon be controlled.
其中，去掉It is that ，句子原本的表达方式应为：
Whether the high price will soon be controlled is not clear.

Answer 2

whether可以引导从句，作主语、表语或同位语，而if不能。如：

正： It was uncertain whether he would come.
误： It was uncertain if he would come.

正： His first question was whether Tom had arrived yet.
误： His first question was if Tom had arrived yet.

正： We must consider the question whether we will take these measures.
误： We must consider the question if we will take these measures.

Answer 3

If也有是否的意思，老师讲过，当 if 和whether同时出现并表“是否”时，必定选whether，能用if的地方一定能用whether，因为whether应用范围比较大，涵盖了if。

Answer 4

if做是否的意思只能用于状语从句，主语、表语从句只能用whether表示是否。

Answer 5

作“是否”讲的时候，用whether 不用if