求各路大神指点啊~B和D怎么就不一样了呢？

konglxd

34. 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 andmust 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

Lhitachii

B的that 和it不能同时在一个句子里面面指代，然后D就是manhattan上说的类似什么estimate，或者phenomenon或者happen之类后面必须要加that做同位语解释说明

konglxd

恩恩！谢谢ls！我没发现前后的平行，还有从句里不能再有指代。。。