OG 08

asus2002

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
E中的错误it没有指代对象和when状语从句表达不对，可以这样理解吗？  谢谢。

rt316

ETS的解释：In B, C, and E, when used by does not parallel amount... used by and nonsensically suggests that the people are used by the equipment.

另：E中it指代不清也的确是个问题

asus2002

谢谢