The stars, some of them at tremendous speeds, are in motion just as the planets are, yet being so far away from the Earth that their apparent positions in the sky do not change enough for their movement to be observed during a single human lifetime.
(This question is from Official Guide. Therefore, because of copyrights, the complete question cannot be copied here. The question can be accessed at GMAT Club)
The sentence seems to present a similarity between stars and planets: both are in motion. It also says that some of the stars are in motion at tremendous speeds. The sentence then presents a contrast that stars are so far away from the earth that the change in their positions in the sky are not large enough to be observable.
There are two problems with this sentence:
- The modifier ‘some of them at tremendous speeds’ is not placed properly. We logically understand that this modifier intends to say that ‘some of them ARE IN MOTION at tremendous speeds’. However, to communicate the same, it needs to be placed after “are in motion”, not before that.
- The sentence intends to provide a contrast using ‘yet’. However, ‘yet’ is followed by the verb-ing modifier, which doesn’t communicate the intended meaning. To communicate the contrast clearly, ‘yet’ should preferably be followed by a clause.
(A) Incorrect. For the reasons described above.
(B) Correct. Both the errors in the original sentence have been corrected. However, this option also makes two other changes in the way the sentence is written. First, the comparison is expressed by using “Like + Noun”, instead of “As + Clause”. Both are valid way of comparing. Also, the comparison in the original sentence and in this option mean the same. Also, ‘yet’ has been replaced by another contrast word ‘but’. So, what we can learn from this option is that the correct option may change some of the correct constructions of the original sentence as well.
(C) Incorrect. For the following reasons:
- When “like + Noun” is placed at the beginning of a clause, it needs to be followed by a comma.
- The presence of two contrast words (‘Although’ and ‘yet’) not only is redundant but also distorts the meaning.
- The adjective phrase “so far…” following ‘yet’ is not joined properly with the sentence. Logically, the phrase should be a part of a separate clause.
(D) Incorrect. When ‘as’ is used to present a comparison, it must always be followed by a clause. When followed by a noun, ‘as’ indicates role or function. For example: As a manager, he is responsible for the welfare of his subordinates. This option, thus, indicates that stars are acting as planets!!
(E) Incorrect. For the following reasons:
- The repetition of ‘are in motion’ is redundant.
- This option means that the planets are at tremendous speeds. Thus, the meaning is different from the original sentence.
- The construction “some of which at tremendous speeds are in motion” is awkward. For clarity, the “tremendous speeds” must appear after “in motion”. It should be “some of which are in motion at tremendous speeds”.
- The whole adjective phrase at the end “so far away from the earth…” now applies to “some of which” – ‘which’ refers to planets. Clearly, the ending adjective phrase was meant for the stars, not the planets.