It is not known whether/if they will come today.

问题描述:

It is not known whether/if they will come today.
It is not known whether/if they will come
还是
It is not to known whether/if they will come

It is not known whether/if they will come 正确不应该是It is not to do sth. 或者: It does not do sth. 吗?这是被动语态,不被人知道 be+动词的过去分词 所以是 it isn't known