把下列句子改成否定句.This ia my brother.It is his book.He is sad.He has a bag.They like red.Mary and Amy are sisters.I have breakfast every morning.Mary likes math.That is my brother.I am happy.She has two sisters.His favorite teacher is Miss Li.Tom gets up at seven.They go to school everyday.They are families.Mr Smith is my art teacher.

This is not my brother
2.that book dosen't his
3.he dosen't sad
4.he don't has a bag
5.they don't like red
6.mary and amy is't are sister
7.l don't have breakfast every morning.
8.mary dosen't likes math.
9.that don't my brother.
10.l an unhapply
11.she dosen't has two sister
12.his favorite teacher don't is miss li
13.tom,gets up at don't seven
14.They didn't go to school every day
15.They are not my family
16.Ms smith is not my art teacher

所有系动词后面加not不就得了！

This isn't my brother.
It isn't his book.
He isn't sad.
He doesn't hasvea bag.
They don't like red.
Neither Mary nor Amy are sisters.
I don't have breakfast every morning.
Mary doesln't ikesmath.
That isn't my brother.
I am not happy.
She doesn't have two sisters.
His favorite teacher isn't Miss Li.
Tom doesn't get up at seven.
They don't go to school everyday.
They aren't families.
Mr Smith isn't my art teacher.

This isn't my brother.
It isn't his book.
He isn't sad.
He doesn't have a bag.
They don't like red.
Mary and Amy aren't sisters.
I don't have breakfast every morning.
Mary doesn't like math.
That isn't my brother.
I am not happy.
She doesn't have two sisters.
His favorite teacher isn't Miss Li.
Tom doesn't get up at seven.
They don't go to school everyday.
They aren't families.
Mr Smith isn't my art teacher.
这主要考查的是你对not这个词的熟练度，要改为否定句，可以直接在be动词或者助动词do/does后面加not，就可以改成否定句了，上面的句子都是按照这种方式来改的。
望采纳~