强调句型的it和引导词it有什么区别？

答 在强调句中，如果去掉It is （was）和that剩下的词仍能重组成一个完整的句子。否则便是引导词it的句型。

1. It was in the street that I saw Tom and Mary. （强调句）

2. It was this morning that I saw Tom and Mary. （强调句）

3. It is because he wants to improve his spoken English that he comes to oral class every day. （强调句）

4. It is natural that you dont understand it all. （引导词）

5. It is a pity that she didnt pass the final exam. （引导词）