at the back of
1. The thief was hiding behind the door.
2. My house is behind the school.
3. The train is behind the time.
4. The sun disappeared behind he clouds.
5. My family is behind me in my ambition to become an engineer.
6. India is behind China in business.
7. Advise him to stand behind the counter.
wihin a specified period of time
1. THEY did nothing during the last week.
2.She will complete this course during the summer vacation.
3. Raise this issue during the discussion.