Hello,xxxx（这里是你要打招呼人,就是帮你安窗户的老外
Hey,xxx
How are you doing?（最近过得怎样）
How are you?
如果他们反问你上面两句,你可以说
I am great.
I am Fine.
I am all right.
I am doing good.
I am wonderful.
跟老外说辛苦你们了,好像不那么表达.
你可以说 Really troubled you a lot!(给你们造成麻烦了）
接下来就可以说感谢的话了!
比如thank you!
thanks!
thanks a lot!
it's very kind of you!
that's very nice of you!
I really appreciate it/your help.
i express my appreciation of your help.
i'm very graterful to you.
i express my gratitude to you.