前面说到简单句有五种句型。
句型1：主语(S)+动词(V)
句型2：主语(S)+动词(V)+补语(C)
句型3：主语(S)+动词(V)+宾语(O)
句型4：主语(S)+动词(V)+间接宾语(o)+直接宾语(O)
句型5：主语(S)+动词(V)+宾语(O)+补语(C)
我们常常需要把有些意思相互结合，也就是改造成更加复杂的并列句和复合句。
有三种方法可以把简单句改造为并列句：
-使用分号。
We fished all day; we didn't catch a thing.
我们钓了一整天鱼，什么也没钓到。
-分号+连接副词。
We fished all day; however, we didn't catch a thing.
-使用并列连词。
We fished all day but (we) didn't catch a thing.
○并列连词可以把不同的简单句变为并列句：
Frank worked hard and became an architect.(句型1+句型2)
I have got a cold so I'm going to bed.（句型3+句型1）
They made him chairman but didn't increase his salary.（句型5+句型3）
Her birthday is next month so I must buy her a present.（句型2+句型4）
按逻辑关系，并列连词一般可分为以下几类：
（一）补充/顺序
He washed the car. He polished it.
→He washed the car and polished it.（并且）
他把车洗了，也抛光了。
→He not only washed the car, but also polished it.（不仅……还）
他不光把车洗了，还抛光了。
→He washed the car and then polished it.（然后）
他把车洗了，然后抛光了。
重点说一下not only...but also...：
对but also后面的内容有强调作用，通常更加令人意外或更加重要。
如上面例句中的：
He not only washed the car,but also polished it.
○如果主语不是代词，那么but或but also有时可以省略，变为not only...+代词形式：
Her interest in your work has not only continued, it has increased.
○also有时可以省略，特别是在比较短的句子中，变为not only...+but...(too/as well)形式，这种情况下，but后面的内容得到更多强调：
He not only washed the car,but polished it too.
He not only washed the car,but polished it as well.
○为了表示强调，not...only可以倒装放在句首，变为Not only be/do/can/will...but (代词) also...的形式：
Not only did he wash the car, but he also polished it.
Not only did he wash the car, he polished it as well.
○not only...but also...不仅可以连接动词，把两个主语相同的简单句变为并列句，同时也可以用于简单句内部来连接形容词、名词、短语，此时也可以用not just可以替换not only：
It is not only the most fashionabe but also one of the best restaurants in the world.
It is not just the most fashionabe but also one of the best restaurants in the world.
它不仅是全世界最时尚的餐厅，同时也是全球最顶级的餐厅之一。
（二）对比/转折
He washed the car. He didn't polished it.
→He washed the car but didn't polished it.（但是）
他把车洗了，但没有抛光。
She sold her house. She can't help regretting it.
→She sold her house, but (she) can't help regretting it.
→She sold her house, yet (she) can't help regretting it.
说一下yet：
○yet作连词，相当于but at the same time，用yet作连词，主语一般需要重复：
I don't eat much, yet I am a size 16.
○有时也见and yet和but yet，意思一样，相当于but：
He's not really nice-looking, and/but yet he has enormous charm.
（三）选择
He speaks French. Or perhaps he understands French.
→He either speaks or understands it.(The speaker does not sure)
He doesn't speak French. He doesn't understand French.
→He neither speaks nor understands French.
either...or...是二选一，要么……要么……，没有第三种选择。
○either的位置通常是在第一种选择前的：
I sppose you find it either funny or boring.
不过在口语中人们常常会把either置于一个动词前：
I sppose you either find it funny or boring.
neither...nor...是两者都否定，既不是……也不是……
○口语中很少使用这个结构
Neither the president nor the Vice President came.
口语中可能更常见的结构是：
The president didn't come and neither did the Vice President.
（四）结果
He couldn't find his pen. He wrote in pencil.
→He couldn't find his pen so he wrote in pencil.
○so后面主语一般要重复并且不使用逗号。
My knee started hurting so I stoped running.
I felt a bit chilly so I put on a jacket.
（五）起因
We rarely stay in hotels. We can't afford it.
→We rarely stay in hotels for we can't afford it.
○LEG上说for的这种用法多出现在书面中，而在CALD中则说明，这是一种过时的用法，《Collins COBUILD English Usage》也说明这种用法多出现在故事体中。
