涉及并列连词and和but的典型试题,有无but和and导致所选答案为什么会变化？

请做以下各组试题，注意其中有无and和but所导致所选答案的变化：
1. It ______ fine, we went out for a walk. (选C)
It ______ fine, and we went out for a walk.(选A)
A. was B. is C. being D. were
2. There I saw five people, the teacher _______.(选A)
There I saw five people, and the teacher _______.(选B)
A. included B. was included C. including D. was including
3. He bought a lot of books, most of _______ are about agriculture.(选D)
He bought a lot of books, and most of _______ are about agriculture.(选A)
A. them B. books C. his D. which
4. He wrote a lot of book, none of _______ were popular. (选D)
He wrote a lot of book, but none of _______ were popular.(选A)
A. them B. books C. his D. which
求详解

这说明你对英语句子结构不了解。在英语中，句与句的连接时需要连词的。例如这里每组句子的第二句都有and或but 做连词，这说明连词之后是一个分句。而每组的第一个句子，你要注意，都是由一个句子和一个独立主格结构所构成的。因为独立主格只是个结构而不是句子，所以他和句子之间不需要连词，所以就没有and或but 出现。
也就是说，英语中的句子结构如下：“句子+连词+句子。” 或者“连词+句子，+句子。”如果出现以下结构“_______，句子。”或“句子，_____。”说明“____"部分的不是句子，而是非谓语结构或者独立主格。

1.简单的说，英语句子中如果有逗号，就要用连词，逗号前面的句子可以有成为一个独立的句子，也就是有主谓宾。It was fine,and we went out for a walk. 如果有逗号没有连词呢，那逗号前面的是非谓语结构或者独立主格，It being fine, we went out for a walk.天晴了我们出去散步了。/Being a student, I must study hard.作为一个学生，我应该努力学习。 2.同样的，the teacher 是被包含，所以选A。中间逗号后面没有连词，不能做独立的句子。 There I 。。。。，and the teacher was included.这个应该也好理解了。 3.如果选A them 和B books,句子中逗号后没有连词显然不对，所以这里需要选which这个关系代词，这里是定语从句。 He bought。。。。，and most of them are about agriculture.这里为什么选A呢，them 代指前面的那些书。 4.同3.

连词成句子