4 Challenging Sentence Correction Problems

Problem involves S-V agreement, Countable noun, Idiom.
Because paper of all kinds is the biggest single component of municipal trash, many municipalities have tried recycling to reduce the cost of trash disposal.
(a) Because paper of all kinds is the biggest single component of municipal trash, many municipalities have tried recycling to reduce the cost of trash disposal.
(b)Because paper of all kinds is the biggest single component in municipal trash, many municipalities tried to recycle so that the cost of trash disposal is reduced.
(c) Because paper of all kinds are the biggest single components of municipal trash, many municipalities have tried to recycle to reduce the cost of trash disposal.
(d) All kinds of paper are the biggest single components of municipal trash, and so many municipalities have tried recycling to reduce the cost of trash disposal.
(e) All kinds of paper is the biggest single component of municipal trash, so many municipalities have tried to recycle so that the cost of trash disposal could be reduced

Solution:
Paper is an uncountable noun, so S-V agreement requires “is” not “are.” Eliminate (c).
“Component of” not “in” is idiomatically correct. Eliminate (b).
“All kinds of paper” is an awkward phrase so eliminate (d) and (e).
The remaining choice (a) is correct.


Problem involves S-V agreement problem
Migraine, the most debilitating common form of headache, afflicts perhaps 18 million Americans, who collectively lose 64 million workdays a year, and they cost the nation $50 billion in medical expenses and lost work time .
(A) year, and they cost the nation $50 billion in medical expenses and lost
(b) year and thus cost the nation $50 billion in medical expenses and lost
(c) year, so as to cost the nation $50 billion in medical expenses and lost
(d) year that costs the nation $50 billion in lost medical expenses and
(e) year, which thus cost the nation $50 billion in lost medical expenses and

Solution:
In SC problems, it helps to rephrase the non-underlined phrase in as a simple terms as possible. Here we have:
Migraine afflicts 18 million Americans, who lose 64 million workdays a year, …

By noticing that “who lose 64 million workdays a year” is parenthetical, it becomes clear that it is Americans that cost the nation $50 billion.
(d) and (e) are wrong because they imply that it is the year that costs $50 billion.
(a) carries the correct sense and meaning but is more awkward than (b) and does not carry the implication sense that “thus” carries.
“so as to” is an awkward expression that is rarely correct on the GMAT, and is wrong here.



Also (d) and (e) are wrong because they imply that the medical expenses were lost.
The answer is (b).


Problem involves S-V agreement, Passive Voice, Idioms
13) Foreign investors, because of their growing confidence in their capability for making profitable investments in the United States, have been led to move from passive involvement in commercial real estate partnerships to active development of their own increasingly ambitious projects.
(a) Foreign investors, because of their growing confidence in their capability for making profitable investments in the United States, have been led
(b) Foreign investors, growing confident about their capability for making profitable investments in the United States, has led them
(c) Growing confidence in their ability to make profitable investments in the United States has led foreign investors
(d) Growing confidence in their ability for making profitable investments in the United States have led foreign investors
(e) Growing confident about their capabilities for making profitable investments in the United States, foreign investors have been led

Usage of the passive “have been led” does not make sense in (a) and (e).
“Foreign investors has” is an S-V agreement error. Eliminate (b).
“ability for doing” is idiomatically wrong. Eliminate (d).
The correct answer is (c)


Problem involves Modifiers, Like vs As.
Unlike other arachnids, which have their nerve cells evenly distributed along their
bodies, the scorpion's nerve cells are clustered in its head, like a mammal's.
(a) bodies, the scorpion's nerve cells are clustered in ~ its head, like a mammal's
(b) bodies, the scorpion's head has a cluster of nerve cells, as a mammal does
(c) body, the scorpion has a cluster of nerve cells in its head, as a mammal does
(d) body, nerve cells are clustered in the scorpion's head, like a mammal's
(e) body, a cluster of nerve cells is in the scorpion's head, like a mammal's

Solution
The easiest way to solve this problem is by examining the modifier.
Consider the sentence without the parenthetical “which … body/bodies” phrase.
The word following “unlike other arachnids,” must be the name of another arachnid, and not the name of a body part.
Answer (c) is the only one that satisfies. It is the correct answer.

Also, not that in (c), “as a mammal does” is correct because “as” is followed by a verb phrase.