妈妈总是警告我们永远不要和陌生人说话。

Mom always warned us to never talk to ___strangers.

我不能就这样走到完全陌生的人面前开始和他们交谈。

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

当我打开门时，我看到一个陌生人站在外面。

When I opened the door, I saw a ___stranger standing outside.