when it comes to sth，真谛是：当波及某事时九游会J9，当说到某事时，在某个方面。

比如：

There's nothing she doesn't know when it comes to computers.说到电脑，莫得她不知说念的事。大意翻译成：在电脑方面她无所不知。

When it comes to fishing, John is an expert.在垂钓方面约翰很在行。

When it comes to math, she is an expert. 当谈到烹数学时，她是个巨匠。

Dad is a pretty smart guy in general but when it comes to common sense, sometimes I wonder about him.爸爸一般情况下很智慧，当波及知识时，无意我对他感到骇怪。

备注：截图来自《小屁孩日志》（DIARY of a Wimpy Kid）