英语中常用的强调句(又称分裂句)结构是"It is/ was+被强调部分+who / that..."。一般来说，被强调部分指人时用who,指物时用that(也可指人)。强调句是把被强调的内容使之成为信息焦点，常用来强调句子的主语、宾语、状语等。例如：

　　She met your brother in Beijing yesterday.这个句子可以改成下列强调句：

　　It was she who met your brother in Beijing yesterday. (强调主语)昨天在北京看见你兄弟的是她。

　　It was your brother that/who/whom she met in Beijing yesterday. (强调宾语)她昨天在北京看见的是你的兄弟。

　　It was in Beijing that she met your brother yesterday. (强调地点状语)她昨天是在北京看见了你的兄弟。

　　It was yesterday that she met your brother in Beijing. (强调时间状语)她是昨天在北京看见你兄弟的。

　　强调句还可以强调宾语补足语、介词宾语和状语从句等。例如：

　　It's dark green that we've painted the kitchen.我们把厨房漆成了深绿色。

　　It's me he gave the book to.他把那本书给了我。

　　It was because he was in a critical condition that the doctors decided to operate on him.医生们之所以决定给他做手术，是因为他病情危险。

　　强调句中的时态一般应一致，即主句与从句的时态应皆用现在时，或皆用过去时，或皆用将来时，其句中的that与who在非正式文体中可以省略。例如：

　　It was the President himself spoke to me.是总统亲自和我谈了话。

　　It was the cat I gave the fish to.我是给那只猫鱼的。

　　强调句中it is/was之后可有一个以上的被强调部分，有时被强调的部分可放在句首。例如：

　　It was she who was lying in the corridor and the stranger who bent over her, "Did I faint?" she asked. (两个被强调的部分是she和the stranger)是她躺在过道上，是陌生人在俯视她。"我晕倒了吗？"她问道。

　　强调句也有一般疑问句形式和特殊疑问句形式。强调句的附加疑问句是针对主句提出的，故其附加疑问句的主语用it,助动词用is/was。例如：

　　What was it that made you so happy?使你这么高兴的到底是什么？

　　Was it you that lost a watch yesterday?昨天是你丢了一块手表吗？

　　Who was it that interviewed you?面试你的是谁呀？

　　It was at this shop that you bought the watch, wasn?蒺t it?你就是在这家商店买的手表，是不是？

　　强调句中的动词形式通常是一般现在时(is)或一般过去时(was)，也可以是带情态动词的形式。例如：

　　It may be his father that you're thinking of.你正在思念的可能是他父亲。

　　It may be my book that he is reading.他正在读的可能就是我的书。

　　It must have been the manager that spoke to you.刚才跟你谈话的一定是经理。

　　强调句与主语从句的区别是：在强调句中去掉it is (was) ... that之后，句子仍然是完整的；而带主语从句的句子则不是这样。在含主语从句的句子里，it is (was)可以换成其他时态(it has been等)，而在强调句中，it之后只能是is或was或情态动词＋be。试比较：

　　It is certain that we shall be late.(主语从句)

　　It is Tom that buys his vegetables in the market. (强调句)

　　强调句与定语从句的区别是：在定语从句中一般使用关系代词that, which，who, whom或关系副词when, where，why等；而在强调句中则主要使用that，who；在定语从句中，先行词(中心词)一般是名词或名词短语，而在强调句中，可以用副词、介词短语或从句来作被强调的内容。试比较：

　　①It is a question that needs careful consideration.

　　②It is novels that Miss Williams enjoys reading.

　　简析：句①是含有定语从句的句子，在此It是指示代词，It is a question是个"主语+系动词+表语"结构，如果去掉It is...that,句子结构就不完整了。句②是强调句，在此It是个引导词，没有具体含义，如果去掉It is...that，把语序稍加调整，句子结构仍然是完整的。再看下面的强调句：

　　It was yesterday that he met your father.是昨天他看到你父亲的。

　　It was not until two decades ago that transistors began to replace electric tubes on a large scale.直到二十年前，晶体管才开始大规模地代替电子管。

　　It was because he was ill (that) we decided to return.正是因为他病了我们才决定回去的。

　　(文/丁元明；英语辅导报初中教师版03~04学年第31期；版权归英语辅导报社所有，独家网络合作伙伴新浪教育，未经许可，不得以任何形式进行转载。)