Hi Rohit,
More than one hundred years ago, students of ornithology reported that hummingbirds can hover
as insects flitting gracefully from one flower to another.
So let’s begin with meaning analysis. The sentence says that more than a century ago, students of ornithology compared hummingbirds with insects. They said that hummingbirds can hover like insects that flit gracefully from one flower to another.
Since the sentence presents comparison, we can use both “like” and “as”. All we need to be careful about is the correct usage of these two words. In comparison sentences, “like” is always followed a noun or a pronoun while “as” is always followed by a clause.
So let’s spot the errors in the original choice. In this comparison sentence, “as” is not followed by a clause by a noun. This usage of “as” followed by a noun to present comparison is incorrect. This is the only error in the sentence.
POE:A. as insects flitting gracefully from one flower to another:
Incorrect for the reason mentioned above.
B. like insects flitting gracefully from one flower to another:
Correct. “Like” is followed by “insects” – a noun.
C. as insects do that flit gracefully from one flower to others:
Incorrect. “that” generally modifies the preceding noun. But here “that” is preceded by a verb. This usage is incorrect.
D. like insects do that flit gracefully from one flower to others:
Incorrect.1. “Like” is followed by a clause “insects do”.
2. Same “that” modification error as in choice C.
E. as do insects that flit gracefully from one flower to some other one:
Incorrect. Phrase “some other one” is wordy. “another” is much concise and precise.
1. While presenting contrast, “like” should be followed by a noun or a pronoun and “as” should be followed by a clause.
2. Use “that” to modify the preceding noun or the head of the preceding noun phrase.
3. Always use concise expressions. They keep the meaning of the sentence clear.
Hope this helps.
Thanks.
Shraddha