1. Nam's still studying English. He started studying it two years ago. (for)

=> Nam has been studying English for two years.

2. I started learning how to play the piano eight months ago. I'm still learning it.

=> I have been learning how to play the piano for the eight months.

3. He attended two online vocational courses: one in 2012 and the other in 2013. (twice)

=> He has attended online vocational courses twice.

4. They visited this college in 2009, 2012 and 2014. (three times)

=> They have visited this college three times.

5. She started her research project last month. She's still doing it.

=> She has been doing her research project for month.

6. The university started building a new campus in May. They are still building it. (since)

=> The university has been building a new campus since May.

7. The graduate students started arriving at four o'clock. They are all in the lecture hall.

=>The graduate students have all arrived at the lecture hall.

8. The last time I cooked was 3 years ago, I haven't cooked for 3 years

=> It's 3 years since the last time I cooked.

9. When did you buy that bag?

=> How long have you bought that bag ?

10. I started writing blog 2 months ago.

=> I have written blog for 2 months.