高中英语it用法总结

　　虚义it指用作没有具体语义的主语，如表示时间、天气、距离、温度等概念的用法。

　　It is a good day.

　　It cost me 10 dollars.

　　高中内容归纳

　　一、形式it:

　　由于句子结构的需要，常常把it作形式主语，而把真正的主语放后置。小伙伴们熟不熟悉！

　　1．形式主语：不定式、动名词以及主语从句作主语时，为避免“头重脚轻”，要将真正的主语后置。

　　It is obvious that he will win the match. （主语从句作主语）

　　It was worthwhile searching for his ''roots.'' （动名词作主语）

　　It took me 10 dollars to buy the book. （不定式作主语）

　　2．形式宾语：当不定式、动名词、that 从句作宾语，又有自己的宾语补语时，要用it 作形式宾语，而把真正的宾语后置。能够用于形式宾语句型的动词有think, make, find, consider, feel, take等。如：

　　Shefound itimportant to study the situation inRussia.

　　The fisherman made it a rule that he never cast his net more than four times a day.

　　The ancient people took it for granted that the earth was flat.

　　We think itnecessary listening to the radio everyday.

　　二、强调it: 为了强调句子中的某一成分，可以用“It is / was ＋ 被强调部分 ＋that / who＋其它”的句型。如：

　　She helped melast week.

　　强调句（强调时间）：It waslast weekthatshe helped me.

　　橙子妈妈要重点介绍的是关于not...until 这一句式结构的强调形式，例如：

　　My dad didn''t come back until 9 o''clock.

　　It wasnot until 9 o''clockthat my dad came back.（记住一定要将not until放在一起，而且从句中的时态需要变化）

　　注意：１）一般强调时间不能用when, 强调地点不用where; ２）强调谓语用下列方式（在谓语动词前面用do diddoes）： I do hate it.

　　三、注意强调句型与定语从句的区别

　　例 It was at 7 o''clock that he came here yesterday.(强调句型)

　　It was 7 o''clock when he came hereyesterday.(定语从句)