1. 不定式的否定式的构成
通常是将否定词not或never置于不定式之前，即构成not to do 或never to do 的形式，注意not和never一定要放在不定式符号to的前面，而不是其后面。如：
I've told you time after time not to do that.
我一再告诉过你不要干那件事。
Be careful not to damage other people's property.
小心别损及别人的财物。
I try not to let work interfere with my personal life.
我尽量不让工作干扰我的私生活。
I trusted her not to go back on her word.
我相信她不会食言。
I find it interesting that she claims not to know him.
她声称不认识他，我觉得真是耐人寻味。
Many people choose not to marry.
许多人情愿不结婚。
I'd prefer you not to make a habit of it.
我希望你不要习以为常。
He crept into the house trying not to make a sound.
他蹑手蹑脚地溜进房子里，尽量不弄出一点声响。
I'm under orders not to let anyone in.
我奉命不准任何人进入。
The doctor advised me not to smoke. 医生劝我不要抽烟。
I vowed never to set foot in the place again.
我发誓再不去那个地方了。
He was never to see his wife again.
他注定再也见不到他的妻子了。
Father warned me never to drive after drinking. 父亲警告我不要酒后开车。
She vowed never to speak to him again.
她发誓再也不和他说话了。
We were fated never to meet again.
我们注定了永远不能再相见。
How many times has your mother told you never to talk to strangers?
你母亲告诉你多少次了，绝不能和陌生人谈话？
Those in his employ were careful never to enrage him.
在他手底下干活的人都非常小心绝不去触怒他。
They swore never to be separated.
他们发誓永不分离。
【注】若不定式为完成式和被动式，否定词应置于整个结构之前。如：
I was sorry not to have seen them.
我很遗憾没有见到他们。
It would be surprising were the Mafia not to have muscled in.
如果黑手党不插上一脚，那反倒令人奇怪了。
She pretended not to have seen him. 她假装没看见他。
She left strict instructions that she was not to be disturbed.
她严格指示不得打扰她。
She was disappointed not to be accepted into the club.
她没有获准加入俱乐部，感到失望。
Not to be outdone, she tried again.
她不甘落后，又试了一次。
He was anxious not to be misunderstood.
他希望不被人误解。
It is nice not to be dependent on others. 不依靠别人是好的。
It was an opportunity not to be missed.
机不可失，时不再来。
These threats are not to be taken lightly.
这些威胁可不能等闲视之。
She was disappointed not to be chosen.
她没有被选中感到很沮丧。
We had to be very careful not to be seen
我们得小心翼翼，不能被发现。
Borrowing used not to be recommended
过去是不建议借贷的。
Tell your husband not to be a cheapskate.
劝劝你丈夫，叫他别那么小气。
2. so as to do sth 和in order to do sth 的否定式
对于这两个结构的否定式，通常是将否定词置于不定式符号to之前，而不是置于整个结构之前或其他位置。如：
I was beginning to feel alarm, but kept it to myself so as not to worry our two friends.
我开始有点慌了，但仍旧不动声色，免得我们的两个朋友担心。
We'll have to be quiet so as not to wake the other roommates.
我们得安静点，免得吵醒其他室友。
She stole out of the room so as not to wake the baby.
她生怕惊醒婴儿，蹑手蹑脚地从屋里出来。
We talked quietly so as not to be overheard.
我们低声交谈，以免别人听到。
We crept around on tiptoes so as not to disturb him.
我们蹑手蹑脚地在周围走动，以免惊动他。
Study hard so as not to fail the exam. 努力学习，以免考试不及格。
We talked quietly so as not to be overheard.
我们低声交谈，以免别人听到。
He promised to be quick so as not to inconvenience them any further.
他许诺尽快完成，以免给他们带来更多不便。
Liz sat down on the bed, lowering herself carefully so as not to crease her skirt.
莉兹小心翼翼地坐在床上，生怕把裙子弄皱。
He came in quietly in order not to wake his wife. 他轻轻进来，以免把他妻子吵醒。
You should decide how many hours you must sleep in order not to experience daytime sleepiness.
你应该决定你必须睡多少小时,以免白天昏昏欲睡。