而B有没有逻辑问题不好说,这题从逻辑意思角度考虑实在不好下手。 本题中的boost的主谓一致是一个考点,而which是boost的主语,因此which指代也应该是个考点,这个问题不该被忽略。支持B的G友谁能告诉我这个which指的是lowering prices还是increasing supply and lowering prices?指代不明可是GMAT中的大忌,凭这一点完全可以排除B。
关于A and B, which的指代,我作了一个小结,请NN指正。
这个which到底修饰谁呢? 我觉得这里正确修饰方法的原则只有一个:没有歧义。
如果A and B中的B为复数(Bs),which后面动词也是复数,which指代会有歧义,让人不知道which到底指的是什么。 As and Bs, which are (which指Bs? 或 which指As and Bs?) A and Bs, which are (which指Bs?或 which指A and Bs?)
下面情况没有歧义: 如果A和B都是单数,which后面动词复数,没有歧义,which修饰A and B。 如果B是单数(不管A是单数还是复数),which后面动词也是单数,没有歧义,which修饰B。 如果B是复数(不管A是单数还是复数)则必须要用which together,没有歧义,这时which修饰A and Bs。
举两个例子: The human nervous system bears a superficial resemblance to a telephone system both because the former carries information in the form of electrical impulses and because all of its neural pathways converge in the brain and spinal cord,which together form a kind of central exchange.
Unlike the shuttle and earlier spacecraft, which were capable of carrying sufficient power in fuel cells and batteries for their short flights, a permanently orbiting space station will have to generate its own electricity.
B选项中although作让步,理应和下半句构成逻辑上的让步关系,而B中下半句只用了一个含糊的被动语态,说需求会因为increasing supply and lowering prices,并未指明increasing supply and lowering prices是由于improved efficiency引起的,从而两个句子脱离了逻辑联系。如果说需求增长的动作发出者不明用了被动,那前半句是干什么呢?
A中则较好的表达这一逻辑联系,it指代improved efficiency,通过(by)increasing supply and lowering prices,从而刺激了需求,这个逻辑链条才是流畅的。而A中thereby作为伴随的结果,也是绝对说得过去的,即便thereby boosting的逻辑主语是improved efficiency,因为这是深层原因