Replace the infinites in brackets by the Present Indefinite, Present Continuous

Replace the infinites in brackets by the Present Indefinite, Present Continuous or Present Perfect Continuous. 1. Where are the pupils? - They (to plant) trees. They (to plant) them since the morning. They always (to plant) trees in October. They already (to plant) several hundred threes this year. 2. Ann (to have) her music lesson now. She (to have) her music lessons twice a week. I am going to take a walk. I (to do) all my home exercies already. I (to do) them for three hours. 4. Since when they (to build) this house? 5. At last I (to find) the book I need. I (to look for) it for a quarter of an hour. 6. Don39;t shout. Helen ( to read) an English book. She ( to work) at her English every day. She ( to learn) this language for three years. She ( to read) many English stories this year. 7. What you (to do) in the morning? 8. What you (to do) since the morning?