open the brackets using correct verb form in perfect continuous tenses1.

Open the brackets using correct verb form in perfect continuous tenses
1. John is in his room, he(to sit) there since the morning.
2. For two hours now we (to talk) about it and we havent come to any conclusion yet.
3. By May my grandfather (to work) at the factory for 20 years.
4. I (to try) to get him on the phone all day.
5. I (to write) the letter for an hour when mother called me.
6. He (to work) on his book for a year soon.