It is (very)likely that从句:(很)可能……;……(很)可能

it 是形式主语,that 从句为真正的主语。比较:

It is likely that he will go.= That he will go is likely.可能他会走。

又如:

It’s very likely that she’ll dance tonight. 很可能今晚她跳舞。

=That she’ll dance tonight is very likely. 很可能今晚她跳舞。

It is likely that the school will have to close. 这家学校可能要关闭。

= That the school will have to close is likely. 这家学校可能要关闭。

It's more than likely that the thieves don't know how much it is worth.

盗贼很可能不知道此物的价值。(more than= very)

It's likely someone gave her a lift, or else that she took a taxi.

可能有人开车捎了她一程,要不就是她打了辆出租车。

《柯林斯高阶英汉双解学习词典》

知识拓展:

as likely as not=most/very likely很可能

As likely as not she's forgotten all about it.

她很可能把这事忘得一干二净了。

一个很实用的句型It is likely that从句