When do you use 唄 instead of 吧 to end a sentence?

Question

I hear a lot of people in mainland China use the former (never from Taiwanese Mandarin) when saying a phrase as a sort of command, but I'm still not sure about why someone would say it.

Answer 1

Their meanings are somewhat different. In a few situations, they are interchangeable, but there are many others where you can only use one and not the other. The key difference is that 呗 is much more assertive, even rhetorical, whereas 吧 can be used to express doubt or uncertainty as well. For completeness I'll cover them all.

Definitions taken from zdic.net

呗

(1) 表示事实或道理明显,很容易了解。如:你不会骑车就学呗

(2) 表示勉强同意的语气。如:你一定要去,就去呗

吧

(1) 用在句末,表示恳求、提议、请求、命令等语气 [(used at the end of a sentence) indicating entreaty, suggestion, command, etc.]。如:派六个人不够吧,我的意见派十个人;你说给大家听听吧!

(2) 用在句末,表示同意、认可的语气 [indicating agreement or acknowledgment]。如:好吧,我一定去;就这样执行吧

(3) 用在句末,表示疑问语气,带有揣度的意味 [indicating doubt]。如:他现在赞同了吧?你弄通了吧?

(4) 用在句末,表示估量、推测语气 [indicating uncertainty]。如:他自己总该知道吧;老王会到这边来吧

(5) 用在句中,表示停顿,带假设语气,并带有列举性质 [indicating a pause]。如:说吧,不好;不说吧,也不好

1. When expressing a foregone or obvious conclusion, you can only use 呗. Let's examine the example:

   你不会骑车就学*呗*

   Here the speaker is saying that the solution, to learn how to ride a bike, is obvious, and doesn't need asking, as if the question was rhetorical. If you change the 呗 to a 吧, then the implication changes:

   你不会骑车就学*吧*

   Here the solution of learning to ride a bike is more of a suggestion, and that other solutions may also be valid.

2. When expressing reluctant agreement, use 呗, although 吧 can also be used. Let's examine this:

   你一定要去,就去*呗*

   Here the speaker is expressing reluctance that "you" have to go. The speaker could replace it with 吧:

   你一定要去,就去*吧*

   But unless expressed elsewhere with tone or context, the tone of this sentence is ambiguous, and not necessarily reluctant.

3. When used as a suggestion or command, you can use either 吧 or 呗:

   你说给大家听听*吧*!

   你说给大家听听*呗*!

4. When expressing agreement or acknowledgement, you would use 吧. Sometimes you can use 呗 as well, but watch out for its more assertive tone:

   就这样执行*吧*

   就这样执行*呗*

5. When used to indicate doubt or uncertainty, you can only use 吧:

   你弄通了*吧*?

   老王会到这边来*吧*

6. There's another special use of 吧, as a pause in speech. In this manner, it is interchangeable with characters like 呢. 呗 doesn't have this usage.

   说*吧*,不好;不说*吧*,也不好

Answer 2

Always use 吧. This is standard/proper Mandarin.

唄 is used in regional dialects.

口 mouth radical indicates the character is meaningless and used purely phonetically. The pronunciation is indicated by the character on the right 贝 (bèi) and 巴 (bā).

Answer 3

Simple answer, use 吧 anytime you want, and if you want to impressive your colleges, you can use 呗.