定语从句中“that”为何词性

　　第一、that 用作形容词（后接复数名词时用those）.
　　它用来指已被提到的人或物；也可表对比,指两个中较远的那个.
　　What about that book you borrowed from me last month?
　　请注意,that 有时候在句子中具有喜欢或轻蔑等感情色彩.
　　that little son of his 他那个小宝贝儿子
　　That George!乔治那家伙!（含有轻蔑语气）
　　第二、that 用作代词.
　　1.that 用作指示代词（复数形式是those）,其指代意义同形容词用法,同时它还可以用作定语从句中的先行词；还可为了避免重复,代替前述名词.
　　That is what he told me.
　　What is that (which) you have got in your hand?
　　The price of rice is higher than that of flour.
　　2.that 用作关系代词,引导限制性定语从句.先行词可人可物,用法相当于who或which.（但是在下列情况下多用that：先行词既有人又有物时；先行词有形容词*、序数词、不定代词、very,only等修饰时；先行词是不定代词时）
　　He talked about the teachers and schools that he had visited.
　　I think it one of the most wonderful films that the film company has ever produced.
　　She has little information that is useful for our research.
　　Is there anything that I can do for you?
　　请注意,that 在定语从句中作宾语时通常可省略.
　　The books (that) I sent you will help you in your studies.
　　第三、that 用作连词,引导名词性从句,状语从句和强调句.
　　1.that名词性从句.
　　①引导宾语从句.及物动词后的引导词that可省略.
　　I didn't expect (that) he could win the championship.
　　The teacher pointed out that Tom was not working hard enough.
　　② 引导主语从句.通常采用it作形式主语的句型.
　　That the earth goes around the sun is known to everyone.
　　（It is known to everyone that the earth goes around the sun.）
　　③引导表语从句.
　　The trouble is that we are short of money.
　　④引导同位语从句.
　　引导同位语从句的that和引导定语从句的that是不同的.前者只起语法作用,在从句中不作任何成分；而后者在定语从句中作主语、宾语或表语.举例说明：
　　The news that he resigned from office surprised us.
　　The idea that he holds is very common nowadays on campus.
　　2.that引导状语从句
　　①引导目的状语从句.
　　Bring it nearer that I may see it better.
　　②引导结果状语从句.
　　What have I done that he should be so angry with me?
　　③引导原因状语从句.
　　I am afraid that I will fail in the driving test.
　　④引导让步状语从句.意为“虽然、尽管”.
　　Difficult that/as the task was,they managed to accomplish it on time.
　　⑤引导条件状语从句.意为“假使、假设”.
　　Supposing that you were in my position,what would you do?
　　On condition that you were lost in the desert,you should ask for help as soon as possible.
　　3.引导强调句.
　　It is Mrs.White that makes the decision in her family,not her meek little husband.
　　It is an ill wind that blows nobody good.
　　第四、that用作副词.
　　1.that用作普通副词.
　　I was that/so angry I could have hit him.
　　2.that用作关系副词.引导定语从句,可以代替when,where,why或 in which,常可省略.
　　I will never forget the evening (that) / when we went to the theatre.
　　The house (that)/where I used to live has been knocked down.
　　第五,与that 有关的常见重要短语.
　　1.in that,意为“既然、因为”.
　　Criticism and self-criticism is necessary in that it helps us correct our mistakes.
　　2.now that,意为“既然、由于”.
　　Now that they have taken matters into their hands,the pace of events has quickened.
　　3.see (to it) that,意为“注意、务必做到、保证”.
　　We will see to it that she gets home early.
　　See to it that you are not late again.
　　4.seeing that,意为“鉴于、由于”.
　　Seeing that it is 8 o'clock,we'll wait no longer.
　　Seeing that he was busy with his work,I didn't disturb him.