red shift

j_shreyans wrote:
OAA

I just want to know why not B.

Often in order to get the right answer to an SC question you have to scan the entire sentence to see things that are not close to the underlined portion and yet still interact with it and affect the answer choice.

In this case, choice B does not work because further along in the sentence is the word by.

Because by appears, we need the underlined portion to be in a form that requires that by.

Choice B therefore does not make sense.

Choice A, on the other hand, because it includes the passive voice expression has been shifted, works well with the by. If we put these parts of the sentence created using choice A closer together, we get has been shifted by.

Hi Marty ,

Just a quick clarification , whats do you mean is that in sentence if BY appears so should i go for first Passive construction?

Please clear and correct me if I took in wrong way.

Thanks,

Hi j_shreyans.

That sounds like a dangerous simplification. There are many sentences that involve the use of the word by and in which the use of the passive voice would not make sense.

Here's one.

Jim found the dog by following its tracks.

The point I was making is one more specific to this question.

In the sentence in the question something was done by the rapid motion. So in the underlined portion we need a construction that fits with that.

The general takeaway here is that you won't be well served by seeking to do well on SC by merely relying on a plethora of rules. The GMAT verbal section is not a test of rules, and the point of it is not to see whether you know nit picky little things such as whether the use of the word by indicates that the passive voice is a better choice. The GMAT verbal section is a test of reasoning skills.

So see this question as a forum for using reasoning skills. In the second half of the sentence you see a construction using the word by. Ok. Is there a simple rule that will get you to the right answer? Not really. What you can do is seek to see what's going on.

Does it make sense to say "light from a galaxy shifting by the rapid motion"? Not really.

Does it make sense to say "light from a distant galaxy has shifted by the rapid motion"? No.

It does make sense to say "light from a distant galaxy has been shifted by the rapid motion." What has happened? The light has been shifted. By whom or what was it shifted? It was shifted by the rapid motion.

That's how you rock SC, by seeing a sentence and its meaning and figuring out what makes sense and what choice creates the most effective sentence.