他如此长时间地从事教学，以至于教学已成了他的第二天性。

He's been teaching for so long that it's second nature to [with, in] him.

youdao

他如此长时间地从事教学，以至于教学已成了他的第二天性。

He's been teaching for so long that it's second nature to him.

youdao

他如此长时间地从事教学，以至于教学已成了他的第二天性。

He's been teaching for so long that it's second nature to him.

youdao