语法不错的人 解释一下呗!!

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 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

Ans: D

请问选项E
                

为什么不能用it 来代而非得用that呢?? 什么情况需要考虑it 和
            that的不同??
                

48. Wisconsin，Illinois, Florida, and Minnesota have begun to enforce statewide bans．prohibiting landfills to accept leaves, brush，and grass clippings.

(A)  prohibiting landfills to accept leaves，brush，and grass clippings

(B)  prohibiting that landfills accept leaves，brush，and grass clippings

(C)  prohibiting landfills from accepting leaves，brush，and grass clippings

(D)  that leaves，brush，and grass clippings cannot be accepted in landfills

(E)  that landfills cannot accept leaves，brush，and grass clippings

Ans: c

为什么选项E中的that所引导的句子
            不能看作是对bans所做的具体说明内容的从句呢??

135.  (31742-!-item-!-188;#058&004710)

At one time, the majestic American chestnut was so prevalent that it was said a squirrel could jump from tree to tree without once touching the ground between New York
            State and Georgia.

(A) so prevalent that it was said a squirrel could

(B) so prevalent that a squirrel was said that it could

(C) so prevalent for a squirrel to be said to be able to

(D) prevalent enough that it was said a squirrel could

(E) prevalent enough for a squirrel to be said to be able to

Ans: A
                

感觉选项A句子写的怪怪的
            请帮我解释一下
            主
            谓语
            ?? 怎么翻译呢?? Chestnut
        是subject , was
        是verb
            

那that 之后
        it
        是subject , was
        是verb 那为什么又多出一个could jump… 乱七八糟了…

这样看起来
        选项B似乎比较好一点吧??

T34:

That为避免重复而指代前面的the amount of energy, it通常指代具体的事物如bird。如果此处用it, 则出现模糊指代，it到底是指the amount 还是energy。

T48，一般情况下不要改变原句的情态动词。我的理解。

135. 

B选项有明显得语法错误:it不知道是指代squirrel 还是前面得主语。

48: 第一，从句没有分词形式简洁，二，cannot没有prohibiting语气合适，是禁止而不是不能。

135：it was said应该是 据说， a squirrel could jump 是宾语从句，看来ets出题也不严密，省了that,

不知这样解释对吗？