听短文，根据短文内容，判断下列句子正误，正确的用“A”表示，不正确的用“B”表示。 短文读两遍。 (     )1. John went to work in a post office before he finished his high school. (     )2. John liked his work. (     )3. John sent letters by driving his car. (     )4. The big dog ran fast to him because he wanted to make John leave. (     )5. The big dog came to pick up the letter for its host. (     )6.The dog was a clerk in a post office. (     )7. The dog was clever.