挑三拣四，请教一个that的替代问题

solome

LZM的语法书中对that替代的解释是that/those相当于前面相对比对象的一部分，仅表
类别或属性，而不包括前面对比对象中的限定语部分。并且给出了一个例子：
The amount of food eaten by me is more than that eaten by him.
此处的that替代the amount of food.

我对这个其实没什么疑问，但是发现og-sc第八题中给出另外一个解释，弄的我有点不
清楚了

8. Lacking information about energy use, people tend to overestimate the amount
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.

D.visible equipment, such as lights, that must be turned on and off and
underestimate that

D, the best choice, correctly parallels the amount... used by with that used by, in
which that is the pronoun substitute for amount.

gemj

THAT当然是指代the amount of energy，否则句子意思不通。
ETS所说的：
that is the pronoun substitute for amount
我想是一种简略的说法，因为在the amount of energy中，中心词是AMOUNT。

solome

恩，我也觉得是这样，但是不敢确认：）