中小学英语夏令营介绍，语气(mood)分三种:直陈语气,祈使语气和虚拟语气.

    虚拟语气是一种特殊的动词形式，用来表示说话人所说的话并不是事实，而是一种愿望，假设，怀疑，猜测，建议。

    “if” 引导的条件句有真实条件句与非真实条件句两种。

    1. 真实条件句所表示的假设

    1) 不随时间而改变的自然法则和客观真理

    2) 可能发生或实现的：if后面的从句用一般现在时，主句用祈使语气或情态动词.

    2. 非真实条件句所表示的假设是不可能发生或不大可能实现的：时态共分两种情况。

    if引导的从句 主句

    a.与现在事实相反 if+主语+动词过去式（be的过去式一律用were） 主语+would+动词原形

    b.与将来事实相反 if+主语+动词过去式（be的过去式一律用were） 主语+would+动词原形

    c.与过去事实相反 if +主语+ had+动词过去分词 主语+would+have+过去分词

    exercises:

    1. 与现在或将来相反

    if you … you would …

    were chairman hu

    were bush

    could choose a place for your house

    won a lottery of 5 million

    your child were addicted to computer games

    came across a blackout in a lift

    2. 与过去相反

    write conditionals based on the following facts.

    1) she didn’t take the medicine, so she felt carsick.

    2) because the sun was in the right direction, the photos came out very well.

    3) the shop didn’t pack the goods properly, so they got damaged.

    4) the government raised taxes, so they were very unpopular.

    5) he wasn’t able to answer all the questions, so he didn’t pass the examination.

    6) he didn’t pass the examination, so he didn’t go to the university.

    7) we didn’t get there on time, so we found the doors locked in our faces.

    8) she didn’t see curse of the golden flower, so she didn’t understand what i said.