it是什么意思呢

It is estimated the project will last four years.

据估计，这项工程将持续四年。

She found it extremely difficult to get a job.

她发觉找工作极其困难。

We estimated it would cost about  5 000.

我们估计要花费大约5000欧元。

It's almost time to go.

是差不多该走的时候了。

There is some doubt about the best way to do it.

这件事怎么做才是最佳办法有点吃不准。