Why don't you ask him? He's a computer expert. It's second nature to him.
干吗不问他？他是个计算机专家，他精通这一行。
It's beyond me.
我不明白。
I'm not cut out for this.
我天生不是干这行的料。
I have a good command of English.
我精通英语。
I'm lost when it comes to using the computer.
碰到计算机的事我就糊涂了。