你不能给艾米那件衬衫——首先，它对她来说太小了。

You can't give Amy that shirt - ___for ___one ___thing it's too small for her.

嗯，首先，你不能一天24小时监视你的臣民——他们不会允许，而且成本会高得离谱。

Well, ___for ___one ___thing, you cannot spy on your subjects 24 hours a day - they would not allow it, and it would be prohibitively expensive.

他拒绝了这份工作；首先，薪水不够。

He declined the offer; ___for ___one ___thing, the salary was inadequate.