1、必修三unit 3 Diverse Cultures语法精讲省略If、状语从句、动词不定式省略句if省略结构在if引导的虚拟语气引导的虚拟语气中：如果从句中含有助动词were，had(done)，should省去if，把were，had，should提到从句句首典例分析典例分析1.If John were here，he would know what to do.Were John here，he would know what to do.要是约翰在这儿，他会知道怎么做。同义句转化(1)典例分析典例分析2.If anything had happened，he would have let
2、 her know.Had anything happened，he would have let her know.要是发生了什么事，他会让她知道的。同义句转化(2)典例分析典例分析3.If it should rain tomorrow,I would stay at home.Should it rain tomorrow，I would stay at home.若是明天下雨，我就待在家里。同义句转化(3)_(shall)he come,the problem would be settled.解析：通过would be settled可判断此句为虚拟语气，从句中省略if，提前shou
3、ld。语法填空。语法填空。考点追击考点追击Should状语从句中的省略可以省去从句的主语和省去从句的主语和be动词动词：1.当从句的主语和主句的主语一致(或者从句的主语为it)；2.从句谓语中包含be动词。典例分析典例分析1.Dontspeakuntil（youare）spokento.2.While（Iwas）walkingaloneinthestreet,Iheardmynamecalled.（1）当从句的主语和主句的主语一致主语一致，且从句谓语中包含包含be动词动词，省去从句的主语和be动词。典例分析典例分析1.IllbuyaTVsetif（itis）necessary.2.Once(i
4、tis)begun，itmustbedonewell（2）当从句的主语为主语为it且从句谓语中包含包含be动词动词时，省去it和be动词。常见短语常见短语if so 如果这样的话 if not 若非如此if ever 如果曾经有的话 if necessary 如果有必要的话if possible 如果可能的话 if any 如果有的话状语从句中的省略（3）例：1.If necessary,ring me.2.If possible,let me know beforehand.When _(expose)to danger and conflict,men tend to increase b
5、lood pressure,feeling nervous or anxious.解析：状语从句中符合省略的条件（主语一致，有be动词），故省略they are.语法填空。语法填空。考点追击考点追击exposed不定式的省略用法用法1 1常在be afraid/glad/happy,expect,forget,hope,intend,like,love,mean,prefer,refuse,seem,try,want,wish等的后面。1.单独使用不定式符号 用来代替动词不定式后面被省略的动词典例典例1.I asked him to see a film,but he didnt want t
6、o(see a film).2.Will you join in the game?-Id be glad to(join in the game).3.-Are you a sailor?-No,but I used to be.1.单独使用不定式符号 用来代替动词不定式后面被省略的动词用法用法2 2（1）当主语部分含有动词do的某种形式时，做表语的动词不定式可省略to。例：The only thing you have to do is（to）press the button.2.省略不定式符号to的情况（1）用法用法3 3（2）不定式作介词but、except的宾语，前面有实义动词do的
7、某种形式时，不定式常省略to。例：Brian had nothing to do but（to）play computer games this afternoon.2.省略不定式符号to的情况（2）用法用法4 4（3）当两个或两个以上的不定式并列时，后面的不定式符号to常省略，但表示对比关系时不省略。例：Im really puzzled what to think of and（to）express.It is easier to make a plan than to carry it out.3.省略不定式符号to的情况（3）用法用法5 5（4）在see、watch、hear、feel
8、、observe、look at等感官动词及使役动词let、make、have后作宾语补足语的不定式不加to，但被动句中要加上to。例：I saw him enter the building.He is often seen to play basketball on the playground.4.省略不定式符号to的情况（4）The city now is much noiser than it used _(be).解析：省略不定式时，如果不定式中含有be、have、have been，通常保留be、have、have been.语法填空。语法填空。考点追击考点追击to beBye-bye!
