补全对话。 A. Have a good trip! B. I'm leaving for California. C. What time is your flight? D. I hope I won't have any difficulty. E.You can buy the guidebook. A: Where are you going on vacation? B: 1 . A: 2 ? B: At 4 on July 20th. But I'm so worried about my English. A: It's quite all right. 3 , a Tour in the USA. B: Good idea. 4 A: Whenever you need help, send me an e-mail or telephone me. I'll help you. B: Thanks very much. I'm leaving on July 20th. Bye. A: Bye. 5 1._____ 2._____ 3._____ 4._____ 5._____