问几个OG上的解释

181. Because of the enormous research and development expenditures required to survive in the electronics industry, an industry marked by rapid innovation and volatile demand, such firms tend to be very large.

(A) to survive

(B) of firms to survive

(C) for surviving

(D) for survival（B）

(E) for firms’ survival

The subject of the main clause (such firms) presumes a prior reference to the firms in question. Furthermore, the logical subject of to survive and the logical complement of required should be made explicit. All three demands are met by B, the best choice. Choices A, C, and D, with no reference to the firms in question, meet none of these demands. In choice E, the illogical and awkward use of a prepositional phrase (for firms’ survival) buries the needed initial reference to firms in a possessive modifier.

181. Because of the enormous research and development expenditures required to survive in the electronics industry, an industry marked by rapid innovation and volatile demand, such firms tend to be very large.

(B) of firms to survive

(E) for firms’ survival


In choice E, the illogical and awkward use of a prepositional phrase (for firms’ survival) buries the needed initial reference to firms in a possessive modifier.


看不懂og上的解释，b和e的区别是什么？

185. The recent surge in the number of airplane flights has clogged the nation’s air-traffic control system, to lead to 55 percent more delays at airports, and prompts fears among some officials that safety is being compromised.

(A) to lead to 55 percent more delays at airports, and prompts

(B) leading to 55 percent more delay at airports and prompting

(C) to lead to a 55 percent increase in delay at airports and prompt

(D) to lead to an increase of 55 percent in delays at airports, and prompted（E）


(E) leading to a 55-percent increase in delays at airports and prompting


og中说the phrase 55-percent increase in delays conveys the meaning more accurately than does the phrase 55 percent more delay (s) in A and B.为什么前者更精确呢？


    

184. As measured by the Commerce Department, corporate profits peaked in the fourth quarter of 1988 and have slipped since then, as many companies have been unable to pass on higher costs.

（A）


(E) yet are slipping since then, because many companies were unable to pass on higher costs

    In E, yet also requires a comma before it, are slipping with since then is illogical, and were unable represents an ungrammatical tense shift.
说yet前面需要加逗号，据我所知，并不是所有的yet都需要,那么og的说法是不是错误呢？