I saw an anecdotal "rule" in a magazine stating that, if an adverb is used in a comparative clause, the '-ly' form of the adverb is preferable to a comparative form. Apparently however, if the adverb does not have an '-ly form, then one can use the comparative form. For example:
- I run quicker than Sara
- I run more quickly than Sara
- I run faster than Sara
The "rule" is that, between the first and second statement, the second statement is to be preferred. However, if 'fast' is used as the adverb, then the comparative form of the adverb is correct; hence, the third statement is also right.
Can someone verify if this "rule" is true and applicable in all situations?