主语从句 导入：观察并指出句子成分 A tree has fallen across the road. You are a student. To find your way can be a problem. Smoking is bad for you. 一．概念： 主语：主语是指句子谈论的主题，说明的人或事物。也就是句中动作、行为、性质和状态的主体，一般位于句首 主语从句：在句中充当主语的从句 二·基本结构 关系词 简单句 谓语动词 宾语 同位语 That he finished writing the composition in such a short time surprised us all. 他在很短的时间内写完作文让我们都很惊讶 三 关系词(引导词) 1． 从属连词：that whether that 引导主语从句只起引导作用，本身无实际意义，在主语从句中不充当任何成分，但不能省略。 That she left him cut him to the heart. That he will come is certain. 注意：有时为了使句子结构平衡, 避免 “头重脚轻”, 常用 it 作形式主语, 而把从句放在后面。E.g That she has made such a mistake is a pity. It is a pity that she has made such a mistake. 这样就构成了下面一些常用句型: 1) It is + adj. +从句 It is necessary that… 有必要… It is important that … . 重要的是… It is obvious that… … 很明显… … 2) It +不及物动词+从句 It seems/appears that... 似乎… … It happened that... 碰巧… … It occurred to me that… … 我突然想起… … 3) It + be +过去分词+从句 It is said that... 据说… … It is known to all that... 众所周知…… It is reported that... 据报道…… It is believed that... 据信……;人们相信…… It is suggested that... 有人建议…… It must be pointed out that... 必须指出…… It has been proved that... 已证明……. 4) It is + n. +从句 It is common knowledge that… …是常识 It is a surprise that …. 令人惊奇的是… It is a fact that…… 事实是…… 由w hether 及其他连词引导的主语从句放在句首，句后都可。 Whether it will please them is hard to say. It is hard to say whether it will please them. 2. 连接代词：who whoever whom whose what whateve...
