都不知道你想问什么了,哎.
1. Teachers always blame students when they make mistakes.
这个句子的确写的不够好.
they既可以说是指teachers,也可以说是指students.
2. The teacher will blame their students when they make mistakes.
这句话写得就有问题,既然主句主语是the teacher,那么后面的宾语就应该说是:his/her students,而不能写成their students了.
如果改成his/her students,则when从句的they只能指students,这倒没有问题.
如果你满意我的答案,敬请点击“选为满意回答” ,谢谢!