请教og中的两道题目233.237！

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233. Recently implemented "shift-work equations" based on studies of the human sleep cycle have reduced sickness, sleeping on the job, fatigue among shift workers, and have raised production efficiency in various industries.

(A)  fatigue among shift workers, and have raised

(B)  fatigue among shift workers, and raised

(C)  and fatigue among shift workers while raising

(D)  lowered fatigue among shift workers, and raised

(E)   and fatigue among shift workers was lowered while raising

答案是c，请教while raising在这里做什么成分，while raising

里面是不是省略的一些句子成分？为什么是raising？

237. It seems likely that a number of astronomical phenomena, such as the formation of planetary nebulas, may be caused by the interaction where two stars orbit each other at close range.

(A)  may be caused by the interaction where two stars orbit each other

(B)  may be caused by the interaction between two stars that each orbit the other

(C)  are because of the interaction between two stars that orbit each other

(D)  are caused by the interaction of two stars where each is orbiting the other

(E)   are caused by the interaction of two stars orbiting each other

Choice E, the best answer, avoids redundancy by using are rather than may be, employs the idiomatic phrase the inter­action of, and expresses the relationship between the stars in a clear, concise way--two stars orbiting each other. In A and B, the use of may be is redundant because the beginning phrase It seems likely that has already established a degree of uncertainty. In A, the phrase the interaction where two stars orbit each other is imprecise and illogical, suggesting that the interaction is a place where the orbiting occurs. In B, the phrase two stars that each orbit the other is both awkward and needlessly wordy. Choice C can be faulted because to form a passive construction, are should take a verb form such as caused rather than an adverb such as because. Also, the phrase two stars that orbit each other illogically suggests that there are two particular stars causing all the phenomena in question, rather than various sets of stars in various loca­tions. In D, the word where has no clear or logical referent, and each is orbiting the other is awkward and unnecessarily wordy; it could be replaced by the clearer and more concise orbiting each other.

请教红体字的部分说得是什么意思？

[此贴子已经被作者于2005-8-17 17:45:07编辑过]

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