ask after

1. 探问; 问起……的健康情况

My mother asked after you.

我母亲问起你的健康情况。

ask for

1. 要, 要求

The miners are asking for another increase in pay.

煤矿工人正在要求再次加薪。

2. 找(人)

There's an old man at the door, asking for you.

门口有一位老人找你。

ask for it

1. 自讨苦吃

If you climb mountains in fog, you're asking for it.

如果你在雾天去爬山, 你是在自讨苦吃。