It was clear the subject pained him. 显然这个问题使他感到很苦恼。

it pains sb to do sth It pained her to think that they would never talk to each other again. 一想到他们将再也不能交谈，她感到十分痛苦。

it pains sb that It pains me that we’ re such hypocrites about it. 我们在这件事上如此虚伪，我感到很痛苦。

His head still pains him from time to time where he got that knock. 他头部被击中的地方还时不时会疼。