because引導的是什麼從句

例句：

They are here because of us.

他們是因為我們來這裏的。

We couldn't understand them because they were talking in Chinese.

我們聽不懂他們在講些什麼，因為他們説的是漢語。

His school work is suffering because of family problems.

由於家庭問題，他的學業日漸退步。

Two players are out of the team because of injury.

兩名隊員因傷退出了比賽。

Why get upset just because you got one bad grade?

何必因為一次成績不好就想不開呢？