it是什么意思呢

　　It is estimated the project will last four years.

　　據估計，這項工程將持續四年。

　　She found it extremely difficult to get a job.

　　她發覺找工作極其困難。

　　We estimated it would cost about  5 000.

　　我們估計要花費大約5000歐元。

　　It's almost time to go.

　　是差不多該走的時候了。

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

　　這件事怎么做才是最佳辦法有點吃不準。