这两个英语句子的区别.

问题描述:

这两个英语句子的区别.
1,Tell him that if he is at home,I'll call to see him.
2,Tell him if he is at home,I'll call to see him.
第一句比第二句多一个that,二者有何区别?

其实第二句就是比第一句省了一个that啊,宾语从句中若that不做从句中的成分是可以省掉的