before -ing ...
2. Think carefully before answering the question. / Before answering the question, think carefully.
3. Mary put on her glasses before reading the letter. / Before reading the letter, Mary put on her glasses.
4. The man took off his coat before getting into the car. / Before getting into the car, the man took off his coat.
after -ing ...
5. We were very tired after walking for three hours. / After walking for three hours, we were very tired.
6. I felt sick after eating too much chocolate. / After eating too much chocolate, I felt sick.
7. I understood the book better after reading it a second time. / After reading the book a second time, I understood it better.
8. John worked in a department store for two years after leaving school. / After leaving school, John worked in a department store for two years.
