【俚语】

You don't say!
（表示惊讶）不会这样吧！不至于吧！
Stop saying that！别说了!

Sally: The Jones boys are keeping a pet snake.
Jones家的小孩养了条宠物蛇。
Alice: You don't say.
不是吧！

You can say that again!
你说得很对！
Mary: It sure is hot today.
今天的确很热啊。
Jane: You can say that again!
说的没错！

Who can say?
谁能说得准?
A: What are you gonna do? Now that you've left the company?
既然你已经离开公司了，你准备干吗？
B: Who can say? Maybe I’ll go abroad.
谁能说得准。或许我会出国。

Having said that
话又说回来，尽管如此

【例句】

He forgets most things, but having said that, he always remembers my birthday.
他总忘事，尽管如此，他一直记得我的生日。

Not say boo
什么也没说，一言未发

【例句】

The neighbor's daughter is just the cutest little thing, but she didn't say boo the whole time we were there.
邻居的女儿是最可爱的，不过我们在那里的时候，她就没有开口说话。