it is uncertain 后用that还是wehther,这两个词分别在什么情况下用?

问题描述:

it is uncertain 后用that还是wehther,这两个词分别在什么情况下用?

记住下面的结构,非常有用:
1 It's certain that -- - .
2 It's uncertain whether - -- - .
3 It is not uncertain that -- - - .