say hi可以单独用吗

不可以。say hi的字面意思是“说一声嗨（你好）”，一般用在say hi to sb.中，意思是“和某人打招呼”。例句：Okay, so say hi to my friend and tell him that you like the hat.

Would you like to come up and say hi to everyone for me?

来向大家打个招呼好吗？

Do you want us to come say hi to her parents?

要我们下去跟对方父母打个招呼吗？

-Say Hi to people and make friends with your colleagues.

-和你的同事打招呼，交朋友。

I thought I'd come by and say hi.

我想我应该过来跟你们问好。

I mean, you don't even say hi to me.

我是说，你还没向我打招呼。