他教学态度认真,可以用英文表示为:

He has a serious teaching attitude.

这个表达来自英文中 serious 这个形容词,serious 的意思是认真的、严肃的。

下面是一些关于 serious 的英文例句及其中文翻译:

He's a very serious person, always thinking about the future. 他是一个非常认真的人,总是想着未来。
This is a serious matter and we need to deal with it immediately. 这是一件严肃的事情,我们需要立刻处理。
She has a serious look on her face, as if something is weighing heavily on her mind. 她面带严肃,好像有什么事情困扰着她。