Verbs after prepositions

Verbs after prepositions

 

 The gerund (-ing form) must be used when a verb comes after a preposition:-

against | at | after | by | on | instead of | talk about | tired of | without

 

For example:

• I am against smoking in public places.
• She is good at speaking English.
• I went home after leaving the party.
• You can improve your English by using the Internet.
• We need to keep on going.
• You should tell the truth instead of lying all the time.
• We can talk about going home.
• I'm tired of hearing excuses.
• You can't learn English without making mistakes.

more info :  http://www.learnenglish.de/grammar/prepositiongerund.htm