英语语法分析

If it's illegal for someone under 21 to drink, it should be illegal for them to drink and drive. That's a no-brainer.

如果不满21岁喝酒是违法的，那他们酒后驾车也应是违法的。这太容易理解了。

《柯林斯英汉双解大词典》

Is proposal of marriage a no-brainer?

求婚是件很简单的事吗？

This one is a no brainer.

这是一个不用动脑子的方法。