Grammar - Before v After v During v While

 Before     After     During     While

 A.    Before     During     After

• Many people get nervous before the final exams.
• I fell asleep during the film.
• We were tired after our visit to the zoo.

 B.    Before     While       After

• Don’t forget to lock all the doors before you go out later.
• My grandmother often falls asleep while she’s watching television.
• They went home after they finished shopping.

 C.    During     While       For

 We use during + noun (during the exams). We use while + verb (while I’m    studying):

• We hardly spoke during the meal.
• We hardly spoke while we were eating. (not ‘during we were eating’)

 We use for  +  a period of time (five days/ three hours/ six years etc)

• I lived in Beijing for a year. (not ‘during a year’)
• We played tennis for three hours. (not ‘during three hours’)

 D.    Before/after  +  -ing (before sleeping / after playing etc)

• I always have breakfast before going to the gym. (not ‘before to go’)
• After doing the shopping, they went for dinner. (not ‘after to do’)
• I started exercising after having my breakfast. (not ‘after to have’)