托福考试改错题常考要点及例题分析（上）Ⅲ
half of =fifty percent
most of + 可数名词 + are
most of + 不可数名词+ is来源：考试大
例：Nearly half of the ancient meteor craters has been
A B C
found in central and eastern Canada.
D
分析：C错，应改为have been。介词of的宾语为复数名词短语，作主语的中心词half当然表复数，相应的谓语动词应为复数形式。
例：Approximately fifty percent of the package utilized
A B
in the United States are for foods and beverages.
C D
分析：A错，应改为packages。从谓语动词用复数形式判断出主语是复数名词。注意food用复数表示不同种类的食品，beverage用复数表示不同种类的饮料，故（C）、（D）均没有错。
(二) 谓语动词的时态来源：考试大 ①、主要考察时间状语
例 The metal aluminum has been first isolated early in the nineteenth century.
A B C D
分析：Metal, aluminum同位语，in the nineteenth century为明显表示过去时间的状语, 因此应该用过去时态，把has been改为was
②、For和since的区别
区别一：For 后面使用时间段，since 后面使用时间点
区别二：Since 只能用在现在完成时态，For 最主要用在现在完成时和一般过去时
I has been a teacher for three years.
I has been a teacher since 1996.来源：考试大 I was a teacher for three years. 这种表达可以，for three years表示一段时间，was 表示过去做了三年，现在不是老师了
例： Since 1921 the budget of the United States became
A B
the primary responsibility of the president.
C D
分析：A错，应改 In. since一般要求主句用完成时态，而句中谓语动词为过去式，其时间状语应与之呼应，故改Since为In。
例：Adella Prentiss Hrghes served as manager of
A B C
the Cleveland Orchestra since fifteen years.
D
分析：D错，应改为for。since引导时间状语时，主句谓语动词为一般完成时；主句谓语动词为一般过去时要用介词for；而且一段时间用for, 而不是since。
52. In general, prawns lived in shallow coastal waters or in streams.
A B C D
自然现象和客观事实用一般现在时态，live
(三) 谓语的语态来源：考试大 语态主要表示是主动语态还是被动语态。 来源：考试大 有四组动词是改错题中常考的：来源：考试大 ①、prove
My advice proved to be wrong. 我的建议被证明是错的
尽管是被证明，但习惯上用主动；
例：A majority of the reports received from people claiming
A
to have seen the legendary Loch Ness Monster have proven to be
B C
mistakes, misconceptions, or they were being tricked.
D
分析：D错，应改为tricks。并列连词 or在此连接名词，如果把D理解为并列句，不仅时态不对，语义也有问题，故将整个句子改为名词。have proven to be是正确的。
②、Locate，Situate
这两个词可以用作主动，表示把…放置在…地方；确定…的位置
Bats locate obstacles.蝙蝠确定障碍物的位置
这两个词也可以用作被动来源：考试大 My school was located near the river.
区分locate的主动和被动比较难，但是有一个技巧存在：locate如果用作主动，后面必须跟宾语
例：The center of gravity of the human body ---- behind the hip joint.
(A)locates来源：考试大
(B)locating
(C)to locate
(D)is located 来源：考试大 分析：空格处显然缺谓语动词，故首先排除不能作谓语的B和C。动词locate后面没有宾语，所以用作被动,表示“位于”，所以D为正确选项。
③、表示需要概念的动词