復合句是考題的基本句子結構，因而連接主句和從句的連接詞就成為重要的命題焦點。TOEEL常考的從屬連詞分三類：（1）關系代詞( that, which ,what who. Whose) (2) 關系副詞（where when why how） (3) 狀語從句連接詞 (where, when, if, though, because…) 掌握有關從屬連詞的試題命題規律，這類題目并不復雜。
從屬連詞常考題型及解題要點
1. 主句與從句之間必須有從屬連詞
例題分析
(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 定語從句關系代詞which引導從句，且在從句中作主語。
(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 空格前后為兩個完整的句子，這里應填入連接詞聯系主從兩句。四個選擇只有wherever是連詞，引導地點狀語從句。
(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 關系代詞who引導定語從句，并作從句的主語。
(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 從屬連詞引導條件狀語從句。
2. 關系代詞 who與which混淆錯用
解題要點：在四個選擇答案中出現who 或者which，應確認它所指代的是人還是物。
例題分析
(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] 關系代詞who指代的是sea，因此應用指物的which或that。
(2)Vaccines for some rare diseases are given only to persons which risk exposure to the disease.
[答案] 關系代詞which指代前面的persons，應改為人稱關系代詞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）中的代詞it是多余的，因為what本身即已包含了先行詞（the thing ） 和關系代詞(that) 。答案（B）中的關系代詞that引導的從句不可以置于介詞的后面。
(5) Most of the food what elephants eat is brought to their mouths by their trunks.
[答案] what應改為that。此句已含有先行詞food，不能再用關系代詞what。
5. 主句和從句
解題要點 主語從句是常考而中國考生又較陌生英文文法結構。主語從句的特點是讀起來有種頭重腳輕的感覺，而且有兩個謂語動詞。連詞That 引導的主語從句應特別留意。因為That 在句中沒有任何意義，它只具有引導出主語從句的功能，因而很容易被忽略。
例題分析
(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引導的主語從句。其中第一個謂語動詞could from 是從句的謂語，第二個系動was是主句的謂語。
(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引導的主語從句。What既是從句的連詞，又是從句的主語。
(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 引導的主語從句。
(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 引導的主語從句，當連續讀到兩個謂語動詞(e.g. helps…is)，而空格在句首，應首先考慮主語從句。這是主語從句典型的句子結構。