Time elapse: 主语 + 时间 + 没 + 动词：e.g. 我两个月没看见我爸爸妈妈了。
Time duration: 主语 + 动词 + 宾语 + 了 + 时间：e.g. 他睡觉睡了13个小时了。
- I have not slept for three days.
- She has been taking a shower for three hours.
- My parents and I have not been phoning each other for two months.
- My roommate has worked in school’s cafeteria for two years.
- I have not seen my parents for five years.
- How long have you been studying Chinese?
- How long has it been since you saw a movie last?
- How often do you visit your teacher in Ohio (俄亥俄)?
- How long has it been since you ate Chinese last?
- She hasn’t had any food for 48 hours.