一.why not句式
why not后习惯上接动词原形，不能接带to不定式或现在分词，主要用于表示同意、赞成、劝诱等，其意为“为什么不……呢”。如：
A：May I go with you? 我可以和你一起去吗?
B：Why not? 可以呀。
Why not try again?干嘛不再试呢?
Why not use both? 何不两者都用?
Why not ask someone else? 问问别人怎么样?
But why not write him from Lisbon? 干吗不从里斯本给他写信?
Why not meet and discuss it? 我们碰个头讨论一下这件事不行吗?
You’re looking tired. Why not take a holiday? 你一脸倦容，怎么不休假呢?
Why not wait till the winter sales to buy a new coat? 为什么不等到冬季大贱卖时再买一件新外衣呢?
If you have to go to the dentist, why not go at once and get it over? 你要是必须去看牙医，为什么不马上就去，一了百了呢?
二.would rather句式
1. “would rather+动词原形”意为“宁愿做某事”，其中的动词原形不能改为不定式或分词。如：
We’d rather stay at home. 我们宁愿呆在家里。
I would rather not tell him. 我宁愿不告诉他。
We would rather not meet him. 我们宁愿不和他相见。
I’d rather work in a supermarket. 我宁愿在超级市场工作。
He would rather listen to others than talk himself. 他宁愿听别人谈而不愿自己谈。
Which would you rather do, go to cinema or stay at home?你是去看电影还是待在家。
I would rather do some reading at home than go shopping with them. 与其和他们去购物，我倒宁愿留在家里读点书。
American young people would rather get advice from strangers. 美国的年轻人宁可从陌生人那里获取咨询。
2. “would rather+动词原形+than+动词原形”意为“宁愿做某事而不愿做另一事”。如：
He would rather play than work. 他宁可玩，却不愿工作。
I’d rather walk than take a bus. 我宁愿走路而不愿乘公共汽车。
He would rather listen to others than talk himself. 他宁愿听别人谈而不愿自己谈。
He would rather deal with a man than with a woman. 他愿意和男人打交道而不愿和女人打交道。
3. “would +动词原形+rather than+动词原形”意为“宁愿做某事而不愿做另一事”。如：
I would do anything rather than let him get off. 我愿做任何事而不愿让他跑掉。
I’d take the slowest train rather than go there by air. 我宁可乘最慢的火车去也不愿坐飞机去。
三、prefer句式
1. prefer+不定式+rather than+动词原形
其意为“宁愿做某事而不愿做另一事”。如：
I prefer to walk there rather than go by bus. 我宁愿走着去，而不愿坐公共汽车去。
He prefers to read rather than watch television. 他喜欢 读书而不喜欢看电视。
注：若语义明确，有时可以有所省略。如：
I prefer to travel by day rather than (travel) by night. 我宁愿白天旅行而不是在夜间旅行。
2. prefer+动名词+to+动名词
其意为“宁愿做某事而不愿做另一事”。如：
He prefers swimming to riding as a sport. 作为一项运动项 目，他更喜欢游泳而不是骑马。
注：这类结构的 prefer 前有时也可用 would, should 等。如：
We would prefer playing outdoors to watching television. 我们宁愿在外面玩而不愿看电视。
