With Subject + Verb
I went to the U.S. after I left school.
With Gerund
I went to the U.S. after leaving school.
Note: Both of them have the same meaning as long as the subject is the same.
Before Jason gets to work, he always buys a milkshake.
Before getting to work, Jason always buys a milkshake.
After I decided, I started to worry about my decision.
After deciding, I started to worry about my decision.
Before you went to Maldives, how did you prepare?
Before going to Maldives, how did you prepare?
After you watch a good movie, what would you like to do?
After watching a good movie, what would you like to do?
Before John became a millionaire, he never enjoyed his life.
Before becoming a millionaire, John never enjoyed his life.
Please turn all the lights off before leaving.
