userashish wrote:In this sentence:

..... Richard wrote his book very enthusiastically and elaborately, and thus it was more popular.

What should replace the dots?

a.Unlike those of his colleagues
b.Unlike books of his colleagues
c.Not like his colleagues
d.Comparing his colleagues
e.Unlike his colleagues

I know option 5 is the correct answer. Why are options 3 and 4 incorrect? What is the correct structure to use for Not like and Comparing?

The version created using option c basically makes sense, but not is usually used with a verb as a means of negation, as in this example.

He is not like the others. That is a negation of He is like the others.

The correct structure to use instead of Not like is Unlike.

The use of option d distorts the meaning of the sentence, as Comparing his colleagues seems to modify Richard wrote his book ..., as if in writing the book he was comparing his colleagues and maybe the book was about his colleagues.

This version makes more sense, I guess. I am not sure that I really like starting with Compared with.

Compared with his colleagues, Richard wrote his book more enthusiastically and elaborately ...

If you want to compare what he did to what his colleagues did you might be best off saying the following.

Richard wrote his book more enthusiastically and elaborately than his colleagues did theirs, and thus ...