1. This last time she came back to her hometown was 4 years ago. (for)
→ She hasn't come back to her hometown for 4 years.
2. He started working as a bank clerk 3 months ago. (for)
→ He has worked as a bank clerk for 3 months.
3. Mr. Minh began to collect stamps in 2000. (since)
→ Mr. Minh has been collecting stamps since 2000.
4. Nga began learning French last year. (since)
→ Nga has learned English since last year.
5. We began living here fifteen years ago. (for)
→ We have lived here for fifteen years.