The modal particle 嘛
A modal particle (语气词) is a function word that adds additional semantic meanings to the sentence or emotionally colors it. It is usually placed at the end of a sentence.
嘛 at the end of a sentence
The particle 嘛 
at the end of a sentence expresses the categorical nature or obviousness of what is said.
It can be translated as “after all”, “indeed” or not translated at all.
at the end of a sentence expresses the categorical nature or obviousness of what is said.
It can be translated as “after all”, “indeed” or not translated at all.Examples
你减肥也可以吃早饭嘛！
You can have breakfast even if you're on a diet!
nǐ jiǎnféi yě kěyǐ chī zǎofàn ma
我还在学嘛
After all, I'm just learning
wǒ hái zàixué ma
The particle 嘛 is often used as a reaction to something you have heard about. The speaker wants to emphasize that his or her statement is unconditionally true and must be accepted by the person he or she is talking to.
Examples
你衣服怎么那么湿呢？—— 外面下大雨嘛！
Why are your clothes so wet? — It’s raining heavily outside!
nǐ yīfu zěnme nàme shī ne — wàimiàn xià dàyǔ ma
The particle 嘛 can be used in a request in which the speaker considers the request obvious.
Examples
你不要说这么大声嘛！
Don’t speak so loudly!
nǐ bú yào shuō zhème dàshēng ma
你想喝酒就自己去嘛
If you want to have a drink, you can go by yourself
nǐ xiǎng hē jiǔ jiù zìjǐ qù ma
Pay attention
The last sentence is a bit rude. It could be the speaker's response to the offer to go for a drink, even though it's quite obvious that he/she can't or doesn’t want to.
嘛 in the middle of the sentence
The particle 嘛 is used in the middle of a sentence to make a pause and emphasize what is being said.
Pay attention
In this case there should be a comma after the particle 嘛.
Examples
开个玩笑嘛，何必当真呢？
I'm joking. Why do you take it so seriously?
kāi ge wánxiào ma, hébì dàngzhēn ne
这个嘛，我也不知道
This stuff, I know nothing about it either
zhè ge ma, wǒ yě bù zhīdào
The phrase 干嘛 “What to do?”
In the colloquial phrase 干嘛 , 嘛 replaces the word 什么 .
In this case, 干嘛 means the same thing as 干什么 — “What to do?”.
, 嘛 replaces the word 什么 .
In this case, 干嘛 means the same thing as 干什么 — “What to do?”. Pay attention
Here 嘛 reads as má.
Examples
她在上海干嘛？
What is she doing in Shanghai?
tā zài shànghǎi gànmá
你干嘛？
What are you doing?
nǐ gànmá
This phrase can also replace the question 为什么 or 怎么 even when there is an indignative intonation:
or 怎么 even when there is an indignative intonation:Examples
你干嘛这样？
Why do you do it?
nǐ gànmá zhèyàng
你干嘛问这个？
Why are you asking that?
nǐ gànmá wèn zhè ge