1.Tenor George Shirley sang more than 20 leading roles at the Metropolitan Opera since having his debut there as Fernando in Cosifan tulle on October 24, 19661.
(A) sang more than 20 leading roles at the Metropolitan Opra since having
(B) sang more than 20 leading roles at the Metropolitan Opra since having had
(C) has sung more than 20 leading roles at the Metropolitan Opra since
(D) has sung more than 20 leading roles at the Metropolitan Opra after
(E) has sung more than 20 leading roles at the Metropolitan Opra subsequently to
2.Even though its per capita food supply hardly increased during two decades, stringent rationing and planned distribution have allowed the People’s Republic of China to ensure nutritional levels of 2,000 calories per person per day for its population.
(A) Even though its per capita food supply hardly increased during
(B) Even though its per capita food supply has hardly increased in
(C) Despite its per capita food supply hardly increasing over
(D) Despite there being hardly any increase in its per capita food supply during
(E) Although there is hardly any increase in per capita food supply for
3.Although the Supreme Court ruled as long ago as 1880 that Blacks could not be excluded outright from jury service, nearly a century of case-by-case adjudication has been necessary to develop and enforce the principle that all juries must be drawn from“a fair cross section of the community.”
(A) has been necessary to develop and enforce the principle that all juries must be
(B) was necessary for developing and enforcing the principle of all juries being
(C) was to be necessary in developing and enforcing the principle of all juries to be
(D) is necessary to develop and enforce the principle that all juries must be
(E) will be necessary for developing and enforcing the principle of all juries being
4.A study commissioned by the Department of Agriculture showed 【that】 if calves exercise and associated with other calves, they will require less medication and gain weight 【quicker】 than do those raised in confinement.
(A) associated with other calves, they will require less medication and gain weight quicker than do
(B) associated with other calves, they require less medication and gain weight quicker than
(C) associate with other calves, they required less medication and will gain weight quicker than do
(D) associate with other calves, they have 【required less medication and will gain】 weight more quickly than do
(E) associate with other calves, they require less medication and gain weight more quickly than
解析：
【that】后面表示“如果…就…”的结果，用一般现在时态。
[ 排除A B ]
【quicker】 第二种判断方法：quicker修饰gain不对，
应改为quickly。
【required less medication and will gain】required…and will gain搭配不对：表示客观性的规律，用一般现在时态。
20.Although early soap operas were first aired on evening radio in the 1920's, 【they】 had moved to the daytime hours of the 1930's when the evening schedule became crowded with comedians and variety shows.
(A) were first aired on evening radio in the 1920's, they had moved to the daytime hours of the 1930's
(B) were first aired on evening radio in the 1920's, they were moved to the daytime hours in the 1930's
(C) were aired first on evening radio in the 1920's, 【 moving to】 the daytime hours in the 1930's
(D) were aired first in the evening on 1920's radio, they moved to the daytime hours of the 1930's
(E) aired on evening radio first in the 1920's, 【they were moved 】 to the 1930's in the daytime hours
解析：【they】指代soap operas，从句意来看，要使用被动。
[ 排除A D ]
【 moving to】把主句变成了分词引导的从句，使整段句子缺少主句
【they were moved 】 让步状语从句用错被动语态。
6..The Olympic Games helped to keep peace among the pugnacious states of the Greek world 【 in that】 a sacred truce was proclaimed during the festival's month.
(A) world in that a sacred truce was proclaimed during the festival's month
(B) world, proclaiming a sacred truce during the festival's month
(C) 【world when they proclaimed a sacred truce for the festival month】
(D) world, for a sacred truce was proclaimed during the month of the festival
(E) world by proclamation of a sacred truce that was for the month of the festival
解析：
【 in that】in that=because
【world when they proclaimed a sacred truce for the festival month】主动优先于被动
[ 排除A D ]
7.The boom in agricultural exports in the early 1970's emptied United Stated grain bins and many were led to thinking that overproduction was now a problem of the past.
(A) many were led to thinking that overproduction was now.
(B) many had been led to thinking of overproduction as if it were.
(C) The thought 【this】 led to was that overproduction had were.
(D) Led many to the 【thought of overproduction as if】 it were.
(E) Led many to think that overproduction had become.
解析：
【this】this指代不清，且在GMAT中不用this来做代词主语，同时该选项表达过于笨拙、复杂。
【thought of overproduction as if】改变了原文overproduction与从句是一体的概念。
8.In astronomy the term "red shift" denotes the 【extent 】 to which light from a distant galaxy has been shifted toward the red, or long-wave, end of the light spectrum 【by the rapid motion】 of the galaxy away from the Earth.
(A) to which light from a distant galaxy has been shifted
(B) to which light from a distant galaxy has shifted
(C) that light from a distant galaxy has been shifted
(D) of light from a distant galaxy shifting
(E) of the shift of light from a distant galaxy
解析：
【extent 】 extent to which是extent的习惯性用法，表示某个动作，达到某种程度。
【by the rapid motion】 主动优先于被动，但这里暗示要使用被动。[排除B]
答案： 1.C 2.B 3.A 4.E 5.B 6.C 7.E 8.A