The driver told me he was once robbed at knifepoint by a hitchhiker.

这位司机告诉我，他曾经被一位搭车者持刀抢劫过。

Every few days, young thugs steal her paltry takings at knifepoint.

每隔几天，一些小流氓就用刀威迫她交出其微乎其微的钱财。

A 77-year-old woman was robbed at knifepoint.

【rob】一名 77 岁老妪遭到持刀抢劫。

She was robbed at knifepoint.  She’s fine but it was scary.

她被用刀逼着抢劫的。 她还好但是很可怕。