这个看似简单,真要细致解剖还需费点时间。<br>一. 先看两个旁证:<br>1. 原则上,从句是相对主句而言的,有从句就有主句。例如,I don't know what he said. I don't know 主谓结构,句子,主句;what he said 主谓结构,句子,由关联词what连接,从句,做及物动词know的宾语,叫宾语从句。<br>再例:This is what he said. this is 完整的主谓结构,句子,是what引导的从句的主句,what he said 有完整的主谓结构,句子,由关联词what引导,做is的表语,叫表语从句。但是,下一个例子有共性,也有点特殊:<br>What he said is right. what he said 是is 的主语(部分),它是一个完整的主谓结构,句子,由what引导,所以叫主语从句。但是,is right不是个完整的主谓结构,不能称为句子,因而,应该不能称为一般意义的主句,或者说主语从句的主句有一定的特殊性。<br>2. One of the boys is going to college this autumn.<br>我们如果仅仅为了理解,也很简单。现在我们研究语法,所以要分析结构。
You may go, only come back early. (only =but)你可以走,但要早点回来。<br>He wants to buy the watch, only he can’t afford it.他想买这块表,但他买不起。<br>注5:however释义<br>adv.无论如何;不管怎样 However hard it may be, do your best.<br>adv.尽管如此;然而 Later, however, he decided to go.<br>adv. (表示惊奇)怎样;怎么 However did you find it?你是怎样找到它的?<br>conj.不管怎样;不管用什么方法 He can go however be like.他想怎么去都行。<br>2、whereas与while的区别<br>1.whereas = while<br>while前后句子之结构要求并列相对,whereas 在结构上则不一定不需要严格平行。(OG12-131)<br>whereas/while这种连词连接的比较成分不要求含义上绝对的平行<br>2.whereas连接的平行比较只要求对比的核心逻辑上有对称关系,不要求对称位置必须是对称名词,下面句子中主从句的主语分别是energy和nuclear power并不是对称名词,但是对比的核心都是“核能发电占总产出能量的份额”,如OG12-131:<br>Over 75 percent of the energy produced in France derives from nuclear power, whereas nuclear power accounts for just over 33 percent of the energy produced in Germany.<br>*:<br>但是如果whereas后面接介词短语,那么主句的开头也必须需要是介词短语(whereas后出现介词短语或者状语都会非常对称)如OG-113:<br>Whereas in mammals the tiny tubes that convey nutrients to bone cells are arrayed in parallel lines, in birds the tubes fo