I"ain't"doing that"cos"I don't want to!Do you understand this sentence？We speak slang words（俚语） sometimes，but it's important to learn formal words to improve our study．This is why a school in Britain is trying stopping informal language by banning（禁止）all slang words．

The London all-girls high school，Harris Academy Upper Norwood，says the ban will let students"express themselves confidently and properly"．Words banned include"ain't"，which can mean"am not"，"is not"，or"have not"．The word"cos"is used for"because"．And"innit"is slang for"isn't it"．

But is slang bad？It's considered incorrect because very few people speak it．It's not normal．Yet language has always changed over time-even Shakespeare made up words．

Slang words are popular among young people．They love their convenience．For example，"Are you busy？"asks a boy．"No，I have nuffin to do，"replies his friend．At the end of the conversation，his friend says，"I have gotta go，cya．"we can understand that his friend isn't busy because he has noting to do．As the friend leaves he means，"I've got to go．See you．"The Internet has influence slang words as they are much easier to write and simpler to say．

The school says the students need to improve their language skills for finding jobs in the future．Do you think banning slang words is the best way？

51．The slang word"ain't"can be used for the following except"___"

A．Am not

B．Do not

C．Is not

D．Have not

52．People think slang is incorrect because___．

A．It is an old type of language

B．Some schools have stopped using it

C．very few people speak it

D．It has not changed over time

53．What does paragraph 4mainly tell us？___

A．The reason why the young like to use slang words