Hello,
pratyakshagarwal. I would have no reservations about any of the six sentences you have written. In addition to the resource mentioned above in another reply, you may find the following tip useful, one that comes from the legendary instructor Ron Purewal (courtesy of
this Manhattan Prep thread on the very topic in question):
the best rule i've found is to test the legitimacy of placing "greater" BEFORE the noun (i.e., as an adjective), vs. the legitimacy of placing "more" BEFORE the noun (i.e., as an adjective). if it works as an adjective, then it should also work in the construction you're describing here.
in this problem, which i'm sure is the problem that prompted your query in the first place, you can clear up the issue of "numbers are greater than..." vs. "numbers are more than..." by doing this inversion:
the gyrfalcon has greater numbers --> this is ok
the gyrfalcon has more numbers --> this doesn't make sense
therefore, "greater" is the preferred version.
try this if you ever run into this issue again; it will almost certainly work.
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I hope all of this information proves helpful to you. Good luck with your studies.
- Andrew