Correct the mistakes in the following sentences. 1. I would live in Nanjing when I was at primary school. 2. The explorer discovered the ancient cave in accident. 3. This course requires that every student turn in a paper of two pages least and four pages most. 4. Debbie is not sometimes responsible for what she does. 5. Nobody knows the exact age of the earth by certain. 6. He raised his arm to protect his face to the blow. 7. the beggar accepted the food and money and gave a performance as return. 8. A stitch on time saves nine. 9. The postman dropped my letter into our neighbor’s mail box through mistake. 10. He sent his parcel by the sea, since airmail was too expensive.