if后面动词的什么形式 if后面接动词的什么形式

【if后面动词的什么形式 if后面接动词的什么形式】在含有条件状语从句的复合句中，表示将来时态，主句是一般将来时态，祈使句或情态动词，if后的从句要用现在时态。

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if虚拟语气的三种时态
1、提出将来会发生的事：主句：主语+would/should/might/could+动词原形;
从句：should+动词原形/were to+动词原形;
2、提出现在的条件：主句：主语+would/should/might/could+动词原形;
从句：动词过去式;
例句：If he studied at this school, he would know the enviornment around the school very much.
3、提出过去的未发生的条件：主句：主语+would/should/might/could have+动词过去分词
从句：had+动词过去分词
例句： If I had read the book, I would have told you about it.