做题多少不重要,重要的是理解和吃透题目,保证自己下次能做出来.
100道题实在太多,如有必须,建议去买本题做比较好.
这里我帮你找了肯定变否定的语法摘要,
一、陈述句的肯定式变否定式
1.谓语动词是系动词 be 、情态动词或助动词时,直接在这些词的后面加上否定词.如：
I am a teacher.→ I am not a teacher.
Li Lei can swim.→ Li Lei cannot （ can't ） swim.
We have learned 3,000 words.→ We have not （ haven't ） learned 3,000 words.
He will go to the zoo if it rains tomorrow.→ He will not （ won't ） go to the zoo if it rains tomorrow.
2.谓语动词是行为动词时,要根据时态选用 do 的相应形式,即 do / does / did not ,并把该谓语动词恢复原形.如：
I get up at six o'clock every day.→ I don't get up at six o'clock every day.
Mr Wang works in a factory.→ Mr Wang doesn't work in a factory.
Xia Lin visited our friends last night.→ Xia Lin didn't visit our friends last night.
3.用含有否定意义的词或词组直接取代肯定句中的某些词或词组.
（ 1 ）肯定句中含有 always 和 ever ,变否定句时改为 never .如：
He is always late for school.→ He is never late for school.
My uncle's ever been to many parts of England.→ My uncle has never been to many parts of England.
（ 2 ）肯定句中含有 nearly ,almost ,变否定句时改为 hardly .如：
Lin Tao nearly knows him.→ Lin Tao hardly knows him.
（ 3 ）肯定句中含有 many ,much,变否定句时改为 few,little .如：
Many students know the man under the tree.→ Few students know the man under the tree.
There is much water in the glass.→ There is little water in the glass.
（ 4 ）肯定句中含有 both,both … and ,all ,变否定句时改为 neither,neither … nor,none .如：
Both of us are students.→ Neither of us is a student.
I know both English and Chinese.→ I know neither English nor Chinese.
All of them like bananas.→ None of them like （ s ） bananas.
（ 5 ）肯定句中含有 every-,some- 的合成词,变否定句时常改为含有 no- 的合成词.如：
Everything is ready.→ Nothing is ready.
There is something wrong with my bike.→ There is nothing wrong with my bike.
（ 6 ）肯定句中含有“形容词＋ enough ”,变否定句时改为“ too ＋形容词的反义词”.如：
She is old enough to go to school.→ She is too young to go to school.
二、祈使句的肯定式变否定式
1.一般情况下,在句首的动词前加 Don't .如：
Close the door.→ Don't close the door.
2.肯定句是“ had better ＋动词原形”,变否定句时改为“ had better not ＋动词原形”.如：
You'd better come to school earlier next time.→ You'd better not come to school earlier next time.
3.以 Let's 或 Let us 开头的祈使句,在变否定句时常在其后加 not ；有时也可在其前加 Don't .如：
Let's play with fire.→ Let's not play with fire.→ Don't let's play with fire.
Let me try again.→ Let me not try again.→ Don't let me try again.
三、复合句的肯定式变否定式
1.一般将主句变为否定式.如：
I was cooking when he knocked at the door.→ I was not cooking when he knocked at the door.
2.在谓语动词是 think,believe,suppose,guess 等的宾语从句中,变否定句时常否定主句.如：
I think he will give you a call.→ I don't think he will give you a call.
四、肯定句变否定句应注意的其他情况
1.动词不定式变否定式时,常在不定式符号 to 前加 not .如：
The teacher asked me to speak more loudly.→ The teacher asked me not to speak more loudly.
2.既要否定谓语动词,又要变换句中的单词（ and 一般要变为 or,some 变为 any,already 变为 yet,too 变为 either ）.如：
He can read and write.→ He can't read or write.
We can see some flowers in front of the house.→ We can't see any flowers in front of the house.
The students of No 2 Middle School have gone for a picnic already.→ The students of No 2 Middle School haven't gone for a picnic yet.