There is substantial evidence that certain forms of solar energy either now or w

游客2024-01-13  18

问题 There is substantial evidence that certain forms of solar energy either now or within a few years will be economically competitive with conventional sources of heat and power.

选项 A、either now or within a few years will be economically competitive with conventional sources of heat and power
B、will either be economically competitive with conventional sources of heat and power within a few years or are so now
C、will be economically competitive with conventional sources of heat and power either now or within a few years
D、either are now economically competitive with conventional sources of heat and power or will be so within a few years
E、are either now or will be within a few years economically competitive with conventional sources of heat and power

答案 D

解析 A、C中无论either…or连接的时间状语放在谓语之前(如A)或放在谓语之后(如C),都易产生误解,使读者认为“现在或者在将来的几年内”这两个不同时段的时间状语共同修饰同一个表将来的谓语动词will be,这显然在修饰上是不可行的。另外,由于either…or结构要求并列成分的形式及功能的一致性(可查阅下一章“平行结构”),把B代回原句,句子可简化为:will be or will are so now,显然后半部分的will are是不能接受的。E中的either之后是一时间状语now,or之后是整个谓语部分,两者的并列同样不能让人接受。而D中,either…or连接两个与不同时间段相对应的不同谓语部分的并列,这种表达不仅在语法上,而且在逻辑上都是正确的:即now和are对应,will be与within a few years,不会存在共用同一谓语的情况。其中so替代与前面相同的表语成分:economically competitive with conventional sources of heat and power。注意:本句的evidence是用同位语从句修饰的。
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