同位语从句属复合句的重要内容，也是高考重要考点之一，学好同位语从句关键应注意下列几点：
一、理解同位语从句的含义，把握同位语从句的实质
在主从复合句中作同位语的从句称为同位语从句。同位语从句一般用that，whether等词引导，常放在fact，news，idea，truth，hope，problem，information等名词后面，说明该名词的具体内容。换言之，同位语从句和所修饰的名词在内容上为同一关系。
例：The news that they had won the game soon spread over the whole school．他们比赛获胜的消息很快传遍了整个学校。
析：they had won the game说明The news的全部内容，因此该句为同位语从句。
二、正确运用同位语从句的引导词，准确把握同位语从句
1．如同位语从句意义完整，应用that引导同位语从句。
例：The general gave the order that the soldiers should cross the river at once．将军下达了战士们立即过河的命令。
析：the soldiers should cross the river at once是the order的全部内容，且意义完整，因此应用that引导同位语从句。
2．如同位语从句意义不完整，需增加“是否”的含义，应用whether引导同位语从句。
例：We'll discuss the problem whether the sports meeting will be held on time．我们将讨论运动会是否会如期举行的问题。
析：the sports meeting will be held on time意义不完整，应加“是否”的含义才能表达the problem的全部内容，因此应用whether引导同位语从句。
3．如同位语从句意义不完整，需增加“什么时候”、“什么地点”、“什么方式”等含义，应用when，where，how等词引导同位语从句。
例1：I have no idea when he will be back．
析：he will be back意义不完整，应加“什么时候”的含义才能表达idea的全部内容，因此应用when引导同位语从句。
例2：I have no impression how he went home，perhaps by bike．
析：he went home意义不完整，应加“如何”的含义才能表达impression的全部内容，因此应用how引导同位语从句。
三、把握同位语从句和定语从句的区别，明确同位语从句和相似从句的界限
同位语从句和定语从句相似，都放在某一名词或代词后面，但同位语从句不同于定语从句。同位语从句对名词加以补充说明，是名词全部内容的体现，且名词和同位语从句的引导词均不在从句中作成分；定语从句对名词加以限制，是名词内容的修饰性定语，且名词和定语从句的引导词均在从句中作成分。
例1：Information has been put forward ____ more middle school graduates will be admitted into universities．（NMET2001上海）
A．while B．that C．when D．as
析：答案为B。more middle school graduates will be admitted into universities是Information的内容，且Information不在从句中作成分，所以该句为同位语从句。应将该句区别于：
It is said that more middle school graduates will be admitted into universities，this is the information ____ has been put forward．
A．what B．that C．when D．as
析：答案为B。that has been put forward为information的修饰性定语，且information在从句中作主语，所以该句为定语从句。
例2：She heard a terrible noise，____ brought her heart into her mouth．（MET91）
A．it B．which C．this D．that
析：答案为B。分析语境含义、句子结构和句子成分可知，该句为非限制性定语从句，先行词为a terrible noise，且它在从句中作主语。应将该句区别于：
I can't stand the terrible noise ____ she is crying loudly．
A．it B．which C．this D．that
析：答案为D。she is crying loudly是the terrible noise的内容，且the terrible noise不在从句中作成分，所以该句为同位语从句。
巩固性练习：
1．The fact ____ she works hard is well known to us all．
A．that B．what C．why D．which
2．The fact ____ he was successful proves his ability．
A．that B．what C．which D．why
3．The news ____ he was kidnapped surprised us GREatly．
A．what B．that C．why D．when
4．His suggestion ____ the meeting be delayed was turned down．
A．which B．that C．／D．it
5．I have no idea ____ he will start．
A．when B．that C．what D．／
6．I've come from the government with a message ____ the meeting won't be held tomorrow．
A．if B．that C．whether D．which
7．The thought ____ he might fail in the exam worried him．
A．when B．which C．what D．that
8．The order ____ the prisoner be set free arrived too late．
A．which B．whether C．that D．what
9．The nurses are trying their best to reduce the patient's fear ____ he would die of the disease．
A．that B．as C．of which D．which
10．He often asked me the question ____ the work was worth doing．
A．whether B．where C．that D．when
Keys: 1-5 AABBA 6-10 BDCAA
