Gerunds after Prepositions

This is a good rule. It has no exceptions!

If we want to use a verb after a preposition, it must be a gerund. It is impossible to use an infinitive after a preposition. So for example, we say:

• I will call you after arriving at the office.
• Please have a drink before leaving.
• I am looking forward to meeting you.
• Do you object to working late?
• Tara always dreams about going on holiday.

Notice that you could replace all the above gerunds with "real" nouns:

• I will call you after my arrival at the office.
• Please have a drink before your departure.
• I am looking forward to our lunch.
• Do you object to this job?
• Tara always dreams about holidays.