一、Parallelism: Concrete Nouns and Action Nouns具体名词与动作名词

　　学过具体名词与具体名词平行，动作名词与动作名词平行。

　　具体名词(concrete nouns)指事物、人物、地方、时间段以及特定的事件，如rock, continent, electron, politician, region, holiday, week。

　　动作名词(action nouns)指动作，由动词组成，如eruption, pollution, nomination, withdrawal, development, change, growth

　　然而平行结构没这么简单，今天我们将学习更难的动名词的平行，动名词分为简单动名词和复杂动名词

　　简单动名词短语(Simple gerund phrases)在短语的开始没有冠词(a、an、the)，如Tracking satellites accurately is important for the space agency.

　　复杂动名词短语(Complex gerund phrases)短语的开始有冠词，如The accurate tracking of satellites is important for the space agency.

　　在GMAT考试中，简单动名词不能与复杂动名词平行，如下面的错误例子：I enjoyed drinking the water AND the wine tasting. Drinking water是简单动名词短语，而the wine tasting是复杂动名词短语，所以错误。

　　应该改为：I enjoyed drinking the water AND tasting the wine.

　　此外，只有复杂动名词短语能够与动作名词平行，如下面的错误句子The rebels demanded the withdrawal of government forces from disputed regions, significant reductions in overall troop levels, raising the rebel flagon holidays, AND a general pardon.

　　Withdrawal、reductions、pardon都是动作名词，而raising是简单动名词，所以不能是平行结构，应该改为：The rebels demanded the withdrawal of government forces from disputed regions, significant reductions in overall troop levels, the raising of the rebel flag on holidays, AND a general pardon.

　　当然了，如果一个动词有动作名词的形式，就不要用复杂动名词的形式，看下面的三个例句体会下

　　Wrong: The rebels demanded the withdrawal of government forces from disputed regions AND releasing certain political prisoners. 动作名词与一般动名词短语不平行，所以错误

　　Wrong: The rebels demanded the withdrawing of government forces from disputed regions AND the releasing of certain political prisoners. 两个动名词短语都有动作名词形式，所以错误

　　Right: The rebels demanded the withdrawal of government forces from disputed regions AND the release of certain political prisoners.

　　总之，名词的平行一共有四种：具体名词与具体名词;动作名词与动作名词;动作名词与复杂动名词;简单动名词与简单动名词。大家要记住哦~

　　二、Adjectives and Participles形容词与分词

　　在一些情况下，形容词可以与现在分词或过去分词平行(现在分词是形容词性，动名词是名词词性，虽然他们写法都以ing结尾，但大家不要弄混)

　　过去分词与形容词平行：A mastodon carcass, thawed only once AND still fresh, is on display.

　　Thawed和fresh都修饰carcass，thawed是过去分词，而fresh是形容词，但他们是平行的，因为它们都起到形容词的作用。

　　形容词与现在分词平行：Only a few feet wide BUT spanning a continent, the railroad changed history.形容词wide与现在分词跨越spanning都起到修饰the road的作用，二者平行。