homes，和to design cities.
toseparate…，其中，理解的难点在separate后面的部分。Separate的宾语forces后面被“acting>”这个现在分词短语限定，into后面两个those告诉我们forces被分成哪些部分了。
拆分：
It seems simple enough
to distinguish between the organism and the surrounding environment
and to separate forces(acting>those that are internal and biological
and those that are external and environmental.
翻译：区分有机体和周围环境似乎很简单;把作用于有机体的力量分为内部生物的力量和外部环境的力量似乎也很简单。
小结：从上两句可以看出，并列的不定式后面还包含定语从句或名词性从句，这增加了找出并列成分的难度，但记得，一步还是找出连词，然后分析每个从句的主干结构，从而透彻地理解整个句子。
除了不定式可以引导并列结构，从句也可以，而且难度更大，因为从句会误导考生找不到主句的主干，请看下句：
Children in low-income families and poor communities are less likely to takeorganized youth sports for granted because they often lack the resources neededto pay for participation fees,equipment,and transportation to practices andgames and their communities do not have resources to build and maintain sportsfields and facilities.
解析：
5. Children in low-income families and poor communities are less likely totake organized youth sports for granted because they often lack the resourcesneeded to pay for participation fees,equipment,and transportation to practicesand games and their communities do not have resources to build and maintainsports fields and facilities .
结构：本句中有三个谓语动词，are less likely to do为主句谓语 ,lack和 do not have
为并列原因状语从句的谓语,主语分为they 和 their communities.
拆分：
Children (in low-income families and poor communities )are less likely(totake organized youth sports for granted)take…forgranted…把…认为是理所应当because they often lack the resources (needed)(to pay for participation fees,equipment,and transportation to practices andgames)and (because)their communities do not have resources (to build and maintainsports fields and facilities ).
翻译：来自低收入家庭和贫穷社区的孩子就很少将社区运动视作理所应当，因为他们经常缺少必须的金钱来支付门票、设备和来回车费，而且他们的社区也没有能力来建设和维持运动场和运动设备。
小结：这句话只有虽然有三个谓语，但主句只有一个，所以一、个才是真正的谓语，其他两个是原因状语从句引导的并列从句的谓语，所以理解这句话需要找出主句的谓语。
总结：长难句中的平行结构可以用不同的方式构成，可能并列成分内部仍然有并列成分，但是重要的还是先找到主干结构，再分析并列句的结构，整合起来，一点点解剖整个句子的意思。
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