吧
ba
Softening speech with "ba"
On a statement, 吧 adds a shrug of uncertainty — "I suppose", "right?".
Statement + 吧
How it works
这样不太好吧 is "that's not really okay, is it?". The 吧 keeps a criticism from landing too hard.
It also marks a guess you expect to be confirmed: 你是老师吧? — you're a teacher, right? That's softer than asking with 吗, because it shows you already believe it.
Examples
zhè yàng bú tài hǎo ba
这样不太好吧。
That's not really okay, is it?
nǐ shì lǎo shī ba?
你是老师吧？
You're a teacher, right?
tā yīng gāi dào le ba
他应该到了吧。
He should have arrived by now, I'd think.