Writing Tip: Avoid the -ing's!
Something I've come across when working on the Improving Sentences questions - the answer is almost never the one that begins with "-ing." For example:
1. He enjoys to swim as well as running.
A) He enjoys to swim as well as running.
Correct answer -> He enjoys swimming as well as running.
C) Swimming, he enjoys as well as running.
D) Running is almost as good as swimming, to him at least.
E) Running and swimming are his two favorites.
Only the second choice ( conveys the correct meaning of the sentence.