单词拼写，每个空格限填一词。

     Mr Black comes from the USA. He lives in New York. He is a __1__(医生). He works at night. And he __2__(睡觉) in the day. He is a little__3__(害羞的). He likes to take a __4__(散步) in a __5__(安静的) place. He likes __6__(狮子). He often goes to the zoo. His wife, Mrs Black is a nurse. It’s ___7___(炎热的) today. There is a pool__8__(在……之后)the house. Look! She is swimming in the pool. Oh, she is __9__(饥饿的) now. Mr Black is __10__(煮)dinner. They’re very happy.

列车运行以什么作间隔？