Can anyone please explain.I assure that I have given Powerprep test 2.

Explanation



The meaning of the sentence is that the birds, the species, are going to decline. As such, you need 3 words in this fashion.

This kind of specie of bird X is precarious in its amount, I.E they are in dangerous BUT at the same time lots of species are in the same situation, falling for years in numbers. So, the scientists are investigating this decline.

Hope this helps.
regards
_________________

I do not understand how they got "falling" for the second blank. Can someone help?

While the cerulean warbler's status may be particularly (i) __________ , it is just one of the many species of migrant birds whose numbers have been (ii) __________ for years. Increasingly, biologists investigating the causes of these (iii) __________ are focusing on habitat loss in the Tropics, where the birds spend the winter.

Actually, we do have a decrease in the numbers of these birds. These numbers falling is continuous over the years.

Now I hope this helps

regards
_________________

Blank 2 and blank 3 should be synonym. The hint is at the last part of the final sentence of the question

I'm sorry but I don't understand the first blank. "While" is the trigger word, so shouldn't secure be right word?

Yes, while is indicating contrast, but the trick here is that it is a contrast in degree as indicated by the adverb "particularly". So, while indicates that the bird is especially affected by the situation affecting all of the birds. Therefore, the first blank should be a term that is a greater degree of peril such as "precarious". Hope that helps!
_________________

Hello from the GRE Prep Club VerbalBot!

Thanks to another GRE Prep Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.