【俚语】

I'll say! 是啊！的确如此！

【例句】

A: Wow, this bookshop has everything.
哇，这家书店什么都有。
B: I'll say! I didn't even know copies of this book still existed!
是啊！我都不知道这本书的复印本依然还有！

Having said that
尽管如此，话说回来

【例句】

It’s expensive. Having said that, I must admit that it is very well made.
是挺贵的。不过话说回来，我必须得承认做的还是很精良的。

I wouldn't say no. 好的

【例句】

A: Do you want to try that new sushi place for lunch?
午饭你想尝尝那家新开的寿司店吗？
B: I wouldn't say no!
好啊。

Not to say 虽不能说是

【例句】

It is unwise, not to say stupid, to quit your first job after only one month.
第一份工作才干1个月就辞掉，这虽说不上愚蠢，但也是不明智的。

Do you know what I'm saying?
你知道我意思吧？

We're in serious trouble. Do you know what I'm saying?
我们有大麻烦了。你知道我意思吧？！