another question

[jiang]

I don't understand the choice of the following sentence:

Rather than _____ trouble, he left.

a. cause b. to cause c. causing d. caused

The key is a. But as far as I know rather than should be followed by parallel parts. So can I choose d?

Thank you.

Jiang

[RonBee]

I think causing trouble would be more likely to be used in a "positive" statement, thus:

• He was causing trouble, so he was expelled from the meeting.