it用法？

　　例句：

　　It doesn't have the market to itself.

　　它未能獨占市場。

　　She lost it, just as I said she would.

　　我就說了吧，她把它丟了。

　　It was a time of peak demand for the product.

　　那是對該產品需求最旺的時期。

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

　　問題不像我預料的那么大。

　　It is estimated the project will last four years.

　　據估計，這項工程將持續四年。