我写的句子,请高手看看有没有语法错误

问题描述:

我写的句子,请高手看看有没有语法错误
I'm so sorry that I won't be able to attend the lecture,because I will be welcoming an old friend.that引导的是什么从句?

应该是没有语法错误.
that引导的是宾语从句中的形容词的宾语,例如:
I am extremely sorry that I have troubled you so much.
I am not sure whether they will agree to such a plan.
当然,because从句后面加上一个时间状语则更好.