将下列两个简单句合并成一个含有非限制性定语从句的复合句。 1. I am reading Harry Porter. It is an interesting book. → ____________________________________________ 2. He failed in the exam. It made his parents very angry. → ____________________________________________ 3. He has two sons. Both of them are doctors. → ____________________________________________ 4. Recently I bought an ancient Chinese vase. The price of it was very reasonable. → ____________________________________________ 5. Last week, two persons came to see the house. Neither of them wanted to buy it.→ ____________________________________________ 6. I have lost the pen. My father bought it for my sixteenth birthday. → ____________________________________________ 7. Do you see the house? The windows of it face south.→ ____________________________________________ 8. He must be from Africa. It can be seen from his skin.→ ____________________________________________ 9. The book is worth reading. He paid 6 yuan for it. → ____________________________________________ 10. She is a teacher of much knowledge. Much can be learned from her. → ____________________________________________