问OG8

8. Lacking information about energy use, people tend to overestimate the amount of energy used by equipment, such as lights, that are visible and must be turned on and off and underestimate that used by unobtrusive equipment, such as water heaters.
(A) equipment, such as lights, that are visible and must be turned on and off and underestimate that
(B) equipment, such as lights, that are visible and must be turned on and off and underestimate it when
(C) equipment, such as lights, that is visible and must be turned on and off and underestimate it when
(D) visible equipment, such as lights, that must be turned on and off and underestimate that
(E) visible equipment, such as lights, that must be turned on and off and underestimate it when

OG的解释说BCE使用when used by呵amount..........used by不一直，而且意思是说是人被设备使用，我百思不得其解啊

我们先排除单复数不一致这个错误来看，我觉得不会出现人被机器使用的意思啊

BCE都是说underestimate it when...,这里的it 可以指代the mount 没错吧？然后后面的when接used by unobtrusive .....的是when 后面省略了it,而这个it 指代the amount。是不是这个it不能省略？

我翻来覆去的读这句子，老读不出会产生“人被机器使用”的歧义

哪位同志解释一下呀？

还有，说A B 漏掉了to be,为什么呀？

这里的句子结构是: people ... when used. 从句里省略了主语，那么应该和主句里的主语一致，就是people are used by equipment.

这里说的to be的省略是指be动词的省略。A,B里都用了that are visible, 首先，主谓不一致，应该是that is visible; 其次，这样的说法不简洁。

哦，这样，谢谢

对，这句话有两个平行

people tend to overestimate the amount of energy used by visible equipment......and underestimate that used by unobtrusive equipment.......

that指代：the amount of energy

还是不明白这里的"to be"是怎么被省略的???

ets意思是visible equipment代替equipment that are visible,避免了用be动词可能造成的单复数不一致问题.并不是说句子中某个to be给省略了