Select the right words to complete this enthusiastic email to a friend.

I already bought a tiny hat for him! I am really looking forward _____ your new pet iguana next week!

The correct answer is to meeting.

The phrase "look forward to" is a special case! The word "to" here is a preposition, not part of an infinitive. Because it is a preposition, it must be followed by a gerund (-ing), making "to meeting" the only correct choice.