复合句是考题的基本句子结构，因而连接主句和从句的连接词就成为重要的命题焦点。TOEEL常考的从属连词分三类：（1）关系代词( that, which ,what who. Whose) (2) 关系副词（where when why how） (3) 状语从句连接词 (where, when, if, though, because…) 掌握有关从属连词的试题命题规律，这类题目并不复杂。
从属连词常考题型及解题要点
1. 主句与从句之间必须有从属连词
例题分析
(1)The spiral threads of a spider*s web have a sticky substance on them _____ insects.
(A) traps (B) trap its (C) which traps (D) which it traps
[答案] C 定语从句关系代词which引导从句，且在从句中作主语。
(2)Angiosperms inhabit relatively diverse environments and may be found ______ higher plants can survive.
(A) there (B) wherever (C) somewhere (D) then
[答案] B 空格前后为两个完整的句子，这里应填入连接词联系主从两句。四个选择只有wherever是连词，引导地点状语从句。
(3)Duke Wellington was a composer. Conductor, and pianist ______ ranked as one of the greatest of all jazz figures.
(A) him (B) although (C) or (D) who
[答案] D 关系代词who引导定语从句，并作从句的主语。
(4) ______ Some of the Earth*s interior heat escapes to the surface.
(A) A volcano erupts (B) A volcano whether erupts
(C) A volcano erupts it (D) If a volcano erupts
[答案] D 从属连词引导条件状语从句。
2. 关系代词 who与which混淆错用
解题要点：在四个选择答案中出现who 或者which，应确认它所指代的是人还是物。
例题分析
(1)Fossil remains indicate that squidlike creatures called belemnites swam in the sea who covered the North American continent 70 million years ago.
[答案] 关系代词who指代的是sea，因此应用指物的which或that。
(2)Vaccines for some rare diseases are given only to persons which risk exposure to the disease.
[答案] 关系代词which指代前面的persons，应改为人称关系代词who。
(3) Essentially, a theory is an abstract. Symbolic representation of ______ reality.
(A) what it is conceived (B) that is conceived
(C) what is conceived to be (D) that is being conceived of
[答案] C what = the thing that (is conceived to be…) .答案（A）中的代词it是多余的，因为what本身即已包含了先行词（the thing ） 和关系代词(that) 。答案（B）中的关系代词that引导的从句不可以置于介词的后面。
(5) Most of the food what elephants eat is brought to their mouths by their trunks.
[答案] what应改为that。此句已含有先行词food，不能再用关系代词what。
5. 主句和从句
解题要点 主语从句是常考而中国考生又较陌生英文文法结构。主语从句的特点是读起来有种头重脚轻的感觉，而且有两个谓语动词。连词That 引导的主语从句应特别留意。因为That 在句中没有任何意义，它只具有引导出主语从句的功能，因而很容易被忽略。
例题分析
(1) _____ xenon could not from chemical compounds was once believed by scientists.
(A) For (B) It was (C) That (D) While
[答案] C That引导的主语从句。其中第一个谓语动词could from 是从句的谓语，第二个系动was是主句的谓语。
(2) ______ to space travelers is high acceleration of deceleration forces.
(A) Danger can be (B) They can be dangerous
(C) What can be dangerous (D) While danger
[答案] C what引导的主语从句。What既是从句的连词，又是从句的主语。
(3) ______ has been a topic of continual geological research.
(A) Did the continents originate (B) How did the continents originate
(C) Have the continents originated
(D) How the continents originated
[答案] D How 引导的主语从句。
(4) ______ progress helps to relieve scarcities is a fact accepted by economists.
(A) Technological (B) That technological
(C)Although technological (D)There is technological
[答案] B. That 引导的主语从句，当连续读到两个谓语动词(e.g. helps…is)，而空格在句首，应首先考虑主语从句。这是主语从句典型的句子结构。