its的名词性物主代词形式是什么

　　例句

　　1. It is less of a problem than I'd expected.

　　问题不像我预料的那么大。

　　2. He didn't make it past first base.

　　他未能跑过一垒。

　　3. It's fascinating to see how different people approach the problem.

　　看到不同的人怎样处理这个问题真是有趣极了。

　　4. It is estimated the project will last four years.

　　据估计，这项工程将持续四年。

　　5. It would be interesting to know what he really believed.

　　了解他的真实信仰会是很有意思的。