HELP? og No. 8

Snazzy

Lacking information about energy use, people tend to overestimate the amount of energy used by equimpment, such as lights, that are visibel and must by turned on and off and underestimate that used by unobtrusive equipment, such as water heaters.
A, equimpment, such as lights, that are visibel and must by 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 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


The answer is D. But why? And which is visible, which is not? thanks

rabbitbug

因为要与and underestimate that used by unobtrusive equipment, such as water heaters.平行, visible 要放在equipment前面, 与unobtrusive对应

Snazzy

thanks, rabbit, that's quite an explanation

sunhx

Equipment such as lights is visible while equipment such as water heaters is not.

Snazzy

but why is water heater unobstrusive? it's visible, isn't it? jsut a machine, right?