In the following, Ron, member, Pls, explain the use of "this " in the answer choice E. I know that "this" in E is wrong, but do not know why.

can I write:
I learn English and this help many persons
or I have to write
I learn English, helping many persons.

By sucking sap from the young twigs of the hemlock tree,// tree growth is retarded by the woolly adelgid, causing needles to change color from deep green to grayish green and to drop //prematurely.

A. tree growth is retarded by the woolly adelgid, causing needles to change color from deep green to grayish green and to drop
B. tree growth is retarded by the woolly adelgid, and this causes the color of needles to change from deep green to grayish green, and their dropping
C. the woolly adelgid retards tree growth, which causes needles to change color from deep green to grayish green, and dropping
D. the woolly adelgid retards tree growth, causing needles to change color from deep green to grayish green and to drop
E. the woolly adelgid retards tree growth, and this causes the color of needles to change from deep green to grayish green, and the their dropping

Hi,

IMO, in the SC question, the 'this' in the option E refers to the subject of the sentence - the woolly adelgid. In this case, however, the adelgid does not cause the color of needles to change. The entire process of retardation of tree growth causes the needles to change color.

In option D, the correct answer, the word 'causing' refers to the entire clause before it (the woolly adelgid retards tree growth). This reference to the entire clause correctly implies that the whole process of retardation, not just the adelgid, is responsible for the change in color.

Would love to be corrected if I am mistaken anywhere.

pls, help.

the word "this" in E is correct or not. Pls, explain, I feel that "this" is wrong but do not know why.

"This" in E is wrong because it refers to the woolly adelgid. "This" cannot refer to the entire clause preceding the comma.



In this example, the first sentence is wrong because the antecedent to "this" is not clear. If you want to replace the word "this" with a noun, you would ask something like this - What helps many people? You learning English or just English? If you want to say that 'your learning English' helps many people, then you would say the second sentence, which is the correct sentence.
If you want to say that English helps many people, then you would just say - I learn English, which helps many people.

Hope this is satisfactory.

do you mean that "this" has to refer to a specific noun not to an preceding idea/preceding clause?

As per the forum rules, we need a verifiable source for the problem before we can deal with this question. If the question is not one of ours or one that is copyright-free, we will have to delete the question..

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Tim Sanders
Manhattan GMAT Instructor