选哪个？为什么？ she wanted to go out last night, but we asked her____. A.not to B.not to do it

A.not to 这是不定式省略的用法，请看下面详解

动词不定式中的省略现象
动词不定式中的省略现象可分为两种情况,一是动词不定式符号to后的动词部分的省略;二是动词不定式符号to的省略.
一,省略动词不定式符号to后的动词部分的情况
1.一些表示心理活动,情感态度的动词或短语,如expect \want \hope \wish \love \hate \decide \plan \mean \try \would like \be ready \be afraid \be glad等后,动词不定式省略to后面的动词部分,但保留to.例如:
(1)-I 'll be away on a business trip.Would you mind looking after my dog
-Not at all .I'd be glad to.
(2)-Will you go with me
-Well ,I 'd like to.
(3)-Will you go home tomorrow
-No.I 'm going to a lecture,or at least I am planning to.
2.不定式作宾语补足语时,省略to后的动词部分,即用to代替整个不定式.例如:
(1)The boy wanted to ride his bicycle in the street but his mother told him not to.
(2)You'd better finish the job on time if he ordered you to.
3.在一些情态动词或助动词ought to \have to \used to \be able to后.例如:
(1)-Must I go now
-No.You don 't have to.
(2)-Are you planning to see your grandfather
-No.But I ought to.
二,省略动词不定式符号to的情况
1.动词不定式作感官动词feel \see \notice \watch \find \hear \listen to \observe和使役动词have \make \let等的宾语补足语时,动词不定式符号to省略.如果这些动词用于被动语态,其后的动词不定式符号to不能省略(但let除外).例如:
(1)We often hear him sing the song at home .
(=He is often heard to sing the song at home.)
(2)The y knew her very well.They had seen her grow up from childhood.
(=They knew her very well.She was seen to grow up from childhood.)
注意:
get作"使,让,叫某人做某事"时,要用get sb. to do s t h.结构.例如:
Mother got Tom to buy a pack of sugar.
2.两个或两个以上的动词不定式由连词and \or \than \but连接时,从第二个不定式起,往往省略不定式符号to.但如果强调对比之意时不省略.例如:
(1)She 'd like to take off her coat and have a break.
(2)The students are taught to read,write and do many other things.
(3)I t 's more difficult to do than to say .(强调语意前后对比)
(4)The teacher came not to punish you but to help you.(强调语意前后对比)
(5)I wondered whether to study or to work.(强调语意前后对比)
3.不定式作表语,用来解释主语或主语从句中do的精确含义时,往往可以省略动词不定式符号to.例如:
(1)The first things he did was go up to her trainer and thank her for all her help during her training.
(2)What we want to do now is lie down and rest.
(3)What a dictionary does is help the students to find out the meaning and the usage of new words .
4.在why或why not引起的表示建议或责问的省略问句中.例如:
(1)Why get so excited
(2)Why quarrel with your mother
(3)Why not join us,Tom
5.在一些类似情态动词词组had better \would rather \had best \rather than \can't but \can't help but等之后.例如:
(1)In China it is important to invest in education rather than increase personal wages.
(2)Jack would rather read than talk.
(3)You'd better put on more clothes,or you'll catch a bad cold.
(4)She dares to go to the lonely island by herself.I can 't but admire her bravery.
6.在美国口语中,用在祈使语气中表示目的的动词come \go \try \run之后的动词不定式符号to可省略,也可不省略.例如:
(1)Come tell me if he arrives.
(2)Go tell your mot her.
(3)Run swim together.
(4)Try open the door again.
(5)Try to open the door again.(不省略语气更强烈)
7.在一些固定短语中,
make believe(假装)
make do(凑合,设法对付)
let slip(说出)
leave go(放手)
hear say(听说)
let pass(忽略)
let be(别打扰).例如:
(1)The teacher didn 't let slip a word to us about the coming exam.
(2)I 've heard say that Mary was about to come .
(3)The boy made believe that he was reading when his father entered .
(4)Let him be.
(5)Don 't leave go(of)the fish.
另外值得注意的几种情况:
1.need作行为动词时,后面接带to的动词不定式;当dare作情态动词时,一般不用于肯定陈述句中;当dare作行为动词时,其后既可接带to的动词不定式,也可接不带to的动词不定式.例如:
(1)I dare to swim across the river.
(2)He dares to say that to his father.
(3)She doesn 't dare(to)answer her teacher 's question.
(4)We need to finish the job before lunch.
2.关于动词help后接动词不定式的问题:一般说来,help后既可接带to的动词不定式,也可接不带to的动词不定式(在美国英语及非正式文体中多见不带to).例如:
(1)Would you like to help me(to)carry the luggage
(2)Help the baby(to)get up,Susan!
3.but \besides \except作介词,后接动词不定式的情况:如果这些介词之前有行为动词do的各种形式,那么这些介词后的不定式不带to,反之则要带to.例如:
(1)She could do nothing but cry .
(2)What do you like to do besides swim
(3)He has no choice but to leave.
4.当like或want在由when \whenever \what \whatever \as \if等引导的状语从句中时,其后往往省略整个动词不定式.例如:
(1)Come whenever you like .
(2)Tom,don 't be nervous.
Take whatever you want!
(3)Do anything as you like.
(4)You don 't have to come swimming if you don 't want.

b
ask sb not to do sth

选A，前面已经说过wanted to go out，后面就不要重复了,not to就可以

B 因为她想在晚上出去 但是我们告诉他不要出去 not to do 不要做某事

选A to 后面 的do it省略了。

a 省略？