it后面加动词的第三人称单数形式、过去式、原形等。

it：pron.(指提到过的或正在谈论的动物或事物)它指婴儿，尤指性别不详者指已知或正在发生的事实或情况。 扩展资料

It is estimated the project will last four years.

据估计，这项工程将持续四年。

It was not a propitious time to start a new business.

那不是营业开张的吉时佳日。

She found it extremely difficult to get a job.

她发觉找工作极其困难。

It would be preferable to employ two people， not one.

雇请两个人比雇请一个更好。

We estimated it would cost about 5 000.

我们估计要花费大约5000欧元