所谓并列句，就是有并列连词连接两个或两个以上的简单句而成的句子。
所谓复合句，就是除主句外还包括一个或一个以上从句的句子。
注意：短句子不等于简单句，长句子不等于复杂句。所谓简单句是指就只有一个主干的句子。
注意：汉语中可以用逗号分隔两个完整的句子，英语中绝对不可以。
英语里面，只要出现两个完整的句子，之间绝对不能出现逗号，而必须有连词连接，或者把其中一个句子化简为分词短语或不定式短语。
单一连词：and、or、but，此种连词可以连接对等的句子，或连接句子中任何对等的成分。
I had just lost 50 yuan and I felt very upset.烦恼
The police had a difficult time, but they were most amused. 有趣
注意：or连接句子的时候，通常用于祈使句后面，翻译为否则。
Obey your boss or you will be fired.
Don’t cheat at exams or others will despise you.
Give me liberty or give me death.
祈使句就是你命令他去做某一件事，加上would you please会显得有礼貌。
A young man and a young woman were sitting behind me.连接主语。
I visited museums and sat in public gardens.连接谓语，相当于连接两个句子，省略了第二个句子的主语。
I entered the hotel manager’s office and sat down.
注意：连接谓语的时候，只要助动词相同，即可省略助动词，谓语动词相同的也可以省略。
After talking off, we were flying low over the city and (were) slowly gaining height, when the plane suddenly turned round and flew back to the airport.
Mary is very happy but John (is) very miserable.
Experience is the father of wisdom, and memory (is) the mother.
Reading makes a full man; conference a ready man; and writing an exact man. -–Francis Bacon
读书使人渊博，交谈使人机敏，写作使人精确。Conference和writing后省略了makes。
I looked at the man and the woman angrily.连接宾语。
He asked me for a meal and a glass of beer.
The railway station was big, black and dark.连接表语
The explanation was simple but very unusual.
He saw two thieves rush out of a shop and run towards a waiting car.连接宾语补语。
Pupils of the school, old and new, will be sending him a present to make the occasion.连接定语
We shall all remember Mr. Page for his patience and understanding and for the kindly encouragement. 连接状语。
注意：or连接对等成分的时候，通常翻译为或者。They will go to the zoo or play volleyball.
I want to have a talk with Mr. Jones or Mr. Smith.
And 也可以表示“然后”，“但是”，“那么”，“则”的意思。
Cease to struggle and you cease to live.停止奋斗，则终止了生命
Idleness is sweet, and it is consequences are cruel.懒惰是甜蜜的，但是其结果是残酷的。
I will set my goal and work toward it.我要明确目标，然后为此努力。
由单一连词衍生的连接词：要么……要么……，either……or……
In answer to these questions I either nodded or made strange noises.
Either Bob or Jim or Sam will be the new vice president of the company.
既不是……也不是……，neither……nor……
He answered me, but he spoke neither slowly nor clearly.
We are worried about Mary, she neither eats nor drinks nor talks.
The story is not interesting nor instructive.教育意义
I have never spoken nor written to her.
