表语从句讲解及专项练习概念：表语从句是在复合句中作表语的名词性从句。

放在系动词之后,一般结构是“主语+系动词+表语从句”可以接表语从句的连系动词有be, look, remain, seem等。

★The trouble is that we are short of money.困难是我们资金短缺。

★That is why stone walls are used instead of fences around New England fields.这就是为什么在新英格兰用石头墙而不用栅栏的原因。

★At that time, it seemed as if I couldn't think of the right word anyhow.当时,我似乎怎么也想不出一个恰当的字眼来。

引导表语从句的词：从属连词that、whether、as though、as if（That引导表语从句时，在口语中，间或可以省略。

）关系代词who, what, which, whom, whose, whatever, whoever, whomever, whichever等；关系副词when, where, why, how, however, whenever, wherever等。

※由从属连词that，whether引导的表语从句。

that在引导表语从句时无词义，而whether有词义，意为、“是否”。

这时主句的主语常常是些抽象名词，如question(问题)，trouble(麻烦)，problem(问题)，result(结果)，chance(可能性)，suggestion(建议)，idea(想法)，reason(理由)等。

表语从句对主句主语进行说明、解释，使主语的内容具体化。

例如：★The trouble is (that) she has lost his money. 麻烦的事是他丢了钱。

★The question is whether we need more ice cream.问题是我们是否还需要一些冰淇淋。

★The problem was that it was too valuable for everyday use.问题是它作为日常之用太贵重了。

★What she couldn’t understand was that fewer and fewer students showed interest in her lessons. 我们不能理解越来越少的学生对他的课不感兴趣。

※由关系代词引导的表语从句。

关系代词who, what, which, whom, whose, whatever, whoever, whomever, whichever等引导表语从句，在句中作主语、宾语、表语，关系代词不能省略。

例如：★The question is which of us should go.问题是我们哪一个应该去。

★The problem was who could do the work.问题是谁能做这项工作。

★That's what he is worrying about.那就是他在担心的事。

★That's what we should do.那是我们应该做的。

※由关系副词引导的表语从句。

关系副词when, where, how, why 除在句子起连接作用外，在从句中还充当时间，地点，方式或原因状语，本身具有词义。

例如：★Go and get your coat. It's where you left it. 去把雨衣拿来。

就在你原来放的地方。

★I had neither a raincoat nor an umbrella. That’s why I got wet through. 我们既没伞也没雨衣，这是我们淋湿的原因。

★That is how mice ruin many stores of grain every year.那就是老鼠是怎样每年损害大量粮食的。

★That is what he is worried about.那就是他所担心的。

※由连词because，as if/as though等引导的表语从句。

★It looked as if it was going to snow.看起来好像要下雪了。

★That's because we never thought of it.这是因为我们从未想过此事。

★It seems as if he didn’t know the answer.好像他不知道答案。

注意A. 表语从句一定要用陈述语序。

False: The question is when can he arrive at the hotel.Right: The question is when he can arrive at the hotel.B. 不可以用if，而用whether 连接表语从句(as if 例外）。

引导宾语从句时可以互换if/whether 位于介词后要用whether位于句首时要用whether。

引导表语从句，主语从句，同位语从句时要用whether。

False: The question is if the enemy is marching towards us.Right: The question is whether the enemy is marching towards us.Right: It looked as if he had understood this question.C.不像宾语从句，在有表语从句的复合句中，主句时态和从句时态可以不一致。

Right: The question is who will travel with me to Beijing tomorrow.Right: The question is why he cried yesterday.D. that在表语从句中不可以省掉。

基本用法表语从句只能置于主句之后，而主句的动词只能是联系动词。

名词性从句在be等系动词后作表语时被称为表语从句例如：★The problem is how we can get the things we need.问题是我们怎样能弄到我们需要的东西。

(how 在表语从句中充当方式状语)★The scissors are not what I need. 这把剪刀不是我所需要的。

(what 在表语从句中充当宾语)★What I told him was that I would find him a good play. 我告诉他的是我会给他找个好剧本。

(what在主语从句中作直接宾语，that作为表语从句的引导词在该表语从句中不充当句子成分，不能省略)★That is what I want to tell you.那就是我想要对你讲的。

(what在表语从句中充当直接宾语)★That is why she failed to pass the exam. 那就是她考试不及格的原因。

(why 在表语从句中充当原因状语) 例题精析：［考题1］The traditional view is ____ we sleep because our brain is “programmed” to make us do so. (2007上海)A. whenB. whyC. whetherD. that［答案］D［解析］下划线处之后是包含一个原因状语从句的表语从句，如果看不出它是充当整个句子结构的表语从句将难以把握整个句子的意思。

因此，应选择可引导名词性从句且不充当任何成分的that。

［考题2］You are saying that everyone should be equal, and this is ____ I disagree. (2004)A. whyB. whereC. whatD. how［答案］B［解析］下划线处的引导词引导系动词is后的表语从句并在该表语从句中充当地点状语(“disagree”属于不及物动词，“I disagree”本身是完整的主谓结构)，下划线应填入引导词where，表语从句“where I disagree”的意思是“我不同意之处、我不同意的地方”。

［考题3］— I drove to Zhuhai for the air show last week.— Is that ____ you had a few days off? (1999)A. whyB. whenC. whatD. where［答案］A［解析］下划线处的引导词引导与系动词is连用的表语从句并在该表语从句中充当原因状语，下划线应填入表示“因此……”(指因某种原因所造成的结果)的引导词why。

［考题4］____ she couldn’t understand was ____ fewer and fewer students showed interest in her lessons. (2000上海)A. What; whyB. That; whatC. What; becauseD. Why; that［答案］A［解析］第一个下划线处的引导词引导主语从句并在该主语从句中充当宾语，特指她所不理解的事情，应填入关系代词型的引导词what；第二个下划线处表示“因此……”(指因某种原因所造成的后果，由why引导对应的名词性从句)而不是“为什么……”(指原因、理由，由because引导对应的名词性从句)，应填入引导词why。

［考题5］____ made the school proud was ____ more than 90% of the students had been admitted to key universities. (2003上海春)A. What; becauseB. What; thatC. That; whatD. That; because［答案］B［解析］第一个下划线处的引导词引导主语从句并在该主语从句中充当主语，特指令校方骄傲的事情，应选用关系代词型的引导词what；第二个下划线处引导表语从句表示原因、理由，应由that引导对应的名词性从句。

［考题6］— Are you still thinking a bout yesterday’s game?—Oh, that’s ____. (2003北京春)A. what makes me feel excitedB. whatever I feel excited aboutC. how I feel about itD. when I feel excited［答案］A［解析］A选项的意思是“令我感觉激动的事物”；B选项的意思是“我觉得激动的任何事物”；C选项的意思是“我对它感觉的方式”；D选项的意思是“令我感觉激动的时间”。