在阅读考试中我们经常会遇到陌生词汇，很多同学都会利用上下文进行猜测，但殊不知我们还可以从标点符号推断出正确答案。如果能有效地掌握这种方法，势必能让考生在考试中减轻压力。
1、破折号
(1)双破折号
双破折号在文章中经常出现，它用来解释说明第一个破折号前面的信息，当这个信息是以生词的形式表现出来的话，有了破折号也就不难理解了。再者，双破折号的信息去掉，也不会影响句子的整体意思。
① Sometimes it is slow: vast bubbles of magma—molten rock from the mantle—inch towards the surface, cooling slowly… . (C4T3P2)
解析：“molten rock from the mantle”用来解释“vast bubbles of magma”，即“地壳中的熔岩”。
② For the so-called power events—that require a relatively brief, explosive release of energy, like the 100-metre sprint and the long jump—times and distances have improved ten to twenty percent. (C4T4P1)
解析：“that require a relatively brief, explosive release of energy, like the 100-metre sprint and the long jump”用来解释“power events”，即“力量型赛事”。
(2)单破折号
单破折是用来解释说明其前面的信息的。
① Half of the world’s 6800 languages are likely to vanish within two generations—that’s one language lost every ten days. (C4T2P1)
解析：“that’s one language lost every ten days”用来解释vanish，表示的是lost，两者意思相同。
② …you can see the rough outlines of what are called tectonic plates—the plates which make up the earth’s crust and mantle. (C4T3P2)
解析：“the plates which make up the earth’s crust and mantle”用来解释“tectonic plates”，即组成地球地壳的板块。
③ Whereas most exercises are designed to build up strength or endurance, plyometrics focuses on increasing power—the rate at which an athlete can expend energy. (C4T4P1)
解析：“the rate at which an athlete can expend energy”用来解释“increasing power”，即“运动员释放能量的速度”。
2、插入语的双逗号
句子中经常会出现插入语，即前后用逗号与整个句子结构分开的短语，句子结构，这个成份如果是做同位语成分的名词短语或者非限定性定语从句，通常是用来解释第一个逗号前面的信息的。
Passive smoking, the breathing in of the side-stream smoke from the burning of tobacco between puffs or of the smoke exhaled by a smoker, also causes a serious health risk. (C3T1P2)
解析：如果学员不认识“passive smoking”，逗号后有解释，即“吸入抽烟者吞吐烟草燃烧的烟雾”。
3、括号
句子中出现的双括号与双逗号和双破折号的功能是一样的，括号内容用来解释说明左半括号前面的名词短语，不影响整个句子的结构。
(1)Some plastics are derived from natural sources, some are semi-synthetic (the result of chemical action on a natural substances). (C5T2P1)
解析：“semi-synthetic”即指(半合成品=天然物质发生化学反应的产物)。
(2)…, in which phenol and formaldehyde (from wood or coal) were initially combined under vacuum inside a large egg-shaped kettle. (C5T2P1)
解析：“phenol and formaldehyde”即指(苯酚和甲醛，源自木头和煤炭)。
(3)…and hexa, a compound of ammonia and formaldehyde which supplied the additional formaldehyde necessary to form a thermosetting resin. (C5T2P1)
解析：“hexa”即指(氨与甲醛的合成物)。
