Choose the correct verb from those in brackets:
6. He --------------- a mill in this town. ( have; has; is having).
7. He --------------- here for the last five years. (worked; is working; has been working).
8. He thanked me for what I ------------. (have done; had done; have been doing).
9. I -------------- a strange noise.(hear; am hearing; have been hearing).
10. I ------------------ him for a long time. (know; have known; am knowing)