１．作人称代词 john likes playing pingpong．/ he always does it in the afternoon．(指代上下文提到的事物)；/ it's time we went home. / how far is it from here to your home ? / it is getting warmer and warmer．/ it's very quiet at the moment．(可指时间、天气、环境等) ２．引导词 ａ．作形式主语，代替由不定式、动名词或从句表示的真正主语。 it's important for us to learn a second language．/ it's no use talking to him．/ it's known to all that the earth goes round the sun． b．作形式宾语，代替由不定式、动名词或从句表示的真正宾语。 we feel it our duty to help others．/ he made it clear that he would leave the city． c．强调结构：it is (was) +被强调部分＋that (或who)… 注意: 在强调结构中，如被强调部分为时间状语或地点状语，其后的连接词也绝不能为when 或where，而应用that 。在复习中，一定要注意句式的不同。 it was in shanghai that i bought the guitar．(that引起强调句) it was shanghai where i bought the guitar．(where引起定从) it was twelve o'clock when we arrived there．(when引起时间状语从句） it was at twelve o'clock that we arrived there．（that 引起强调句） 3. it，one，that 的区别：作为代词，这三个词的对比使用是
高考的热点之一。 nmet2000，23． ---why don't we take a little break? ---didn't we just have __________? a．it b．that c．one d．this nmet2001，25 ．
