什么是英语条件句？具体？ 分类？

什么是英语条件句？具体？ 分类？

句子(句子分类，句型转换）
句子的分类:由句子结构来讲，可分为三类简单
一、简单句：由一个主语(或并列主语)和一个谓语（或并列谓语）构成的句子。
eg. We cleaned the windows and tidied the room.

二、并列句：由并列连词and, but,so,or,for等把两个或两个以上的简单句连起来的句子。
eg. 1)I come from China and he comes from Japan.
2)Hurry up,or you'll miss the train.
3)He looked for it everywhere, but he couldn't find it.
4)She didn't know the answer to the question,so she asked the teacher.
5)He's interested in music while John is interested in sports.

三、复合句
A.宾语从句：宾语从句在复合句中作主句的宾语，引导宾语从句的关联词有that, if/whether, what, who, whose, which, why, when, where, how等。

1、连接词
1) 由连接词that引导陈述句，在口语中that常省略。
eg. He said that he would like to see the headmaster.

2)由连接词whether/if引导一般疑问句，whether和if 常可互换，但下列场合一般用whether.
①介词后的宾语从句：I'm thinking of whether he'll come.
②与or not连用：I don't know whether I should go or not.
3)由连接代词what,who(whom,whose)which或连接副词when,where,why,how引导特殊疑问句。 eg. Do you know who/whom she is waiting for?

2、语序：不管宾语从句是陈述句、一般疑问句或特殊疑问句，都要用陈述句语序，也就是说主谓次序不能颠倒。连接词＋主谓结构
(1).Bill wanted to know who did this.
(2).I don't know what's the matter with Bob?
(3).I don't know what's wrong with them?

3、时态：一般说来，主从句时态要统一。如果主句是一般现在时，从句可根据需要用其它任何时态；如果主句是一般过去时，从句应该用相应的过去时态范畴（也就是用一般过去时，过去进行时，过去将来时，过去完成时）。
eg.①Lily wanted to know whether her grandma liked the handbag.
②I asked the teacher where we would have the meeting.
③Could you tell me how I can get to the zoo?

如果从句表明的是一个客观事实或真理，那么无论主句是什么时态，从句都只能用一般现在时。 eg. The teacher told us that light travels much faster than sound.

注意：在think后的宾语从句，如果需要表示否定意义，一般不在宾语从句中否定，而是在主句中否定。
eg. I don’t think that English is easy.
I think that English is not easy. ( 误)