空格所缺为实义词，测试重点不是选择项之间词义和词形的比较辨异，也不是它们的语法内容或惯用搭配，而是短文的理解。这类空缺脱离了上下文就无从确定选哪项。只对空格所在句句子的理解是不够的，考生只有在理解上下文的基础上，才能进行答题，这类空格在各类水平考试的完形填空中占相当大的比重。如下例是MET中的完形填空，其中有14题属于上下文语义题：
Among the early Greeks，Aristotle was 1 to watch living things and to try to classifY them，to attempt to find out 2life begins，and to write down his observation.
His methodswork with the catfish ale typical 3his procedures.He spent hour4hour al the stern of a small boat5 the coast of Lesbos t)n the Aegean Sea leaning far out6 the clear，shallow water，looking down at a catfish that7 its eggs among the reeds.8 he watched，he held his boat steadywith a strong pole9 it would not float away.Later he made a record oI10he halt seen.
So dayafter day from the stern 0f his small boat near the shore.Aristotle watched the life 0f the underwater world11itself.Everyone12fish before.and the fishermen knew something about their habits， 13this knowledge helped them t0 get a bigger catch.But until then14 had watched the ways 0f fish15 the single purpose of trying to undemtand them.
Aristotle thought that 16 he observed each living thing carefully enough and recorded what he saw，he would come closer 17 life.He had great patience and extraordinary powers 0f observation，and 18 these two essential qualities he had an imagination which19 it possible for him to20what he saw.
1.A.a manB.a scientistC.firstD.the first
2.A.whatB.whichC.howD.that
3.A.0fB.forC.inD.from
4.A.bvB.t0C.fromD.after
5.A.offB.inC.t0D.with
6.A.inB.underC.overD.by
7.A.1aidB.was lyingC.1iedD.was laying
8.A.IfB.ThoughC.AsD.Since
9.A.thatB.so thatC.whichD.so as to
10.A.whatB.thatC.whichD.when
11.A.to revealB.to be revealingC.revealedD.revealing
12.A.sawB.have seenC.has seenD.had seen
13.A.forB.withC.inD.about
14.A.oneB.not oneC.no oneD.man
15.A.forB.withC.because ofD.in
16.A.whetherB.ifC.whenD.as
17.A.to be understoodB.t0 an understanding
C.to an understanding ofD.understand
18.A.exceptB.except forC.besideD.besides
19.A.thoughtB.madeC.consideredD.caused
20.A.interpretB.translateC.declareD.pronounce