stranger|strangers

我母亲总是警告我不要和陌生人说话。

My mother always warned me not to talk to ___strangers.

我不能就这么走到一个完全陌生的人面前开始和他们说话。

I can't just walk up to a complete ___stranger and start talking to them.

那个陌生人走到我面前，问我是否能认出他。

The ___stranger came in front of me and asked if I could recognise him.