"in ten minutes 多用于将来时But if seriously,suppose the time now is 2 o'clock sharp,and I say"I will be free in ten minutes." The sentence means I will be free before 2:10 but near 2:10 or after 2:10 and close to 2:10.after ten minutes 一般用于一般时态，如He studiedin the classroom,after 10 minutes,he went out.