相比其他类型网络计划，双代号时标网络计划的突出优点有（）。 A.可以确定工期 B.时

根据对话内容，从方框内的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。
Mrs. Lee: Hello. 68178502.
David:  Hello.  小题1:  ?
Mrs. Lee: Sorry.  小题2: . Can I take a message?
David:  Yes. This is David, Bruce’s friend. I want to ask him for some Chinese ancient coins. He told me he had got some recently.  小题3:  . I don’t care if they were made of different metals. I just want to add some more coins in my collection.
Mrs. Lee: OK. I’ll tell him. Would you like him to ring you back later?
David:  Well, I won’t be at home later this day. Would you please ask him to ring me tomorrow morning?
Mrs. Lee: Sure. 小题4: ?
David:   Oh, sorry.  小题5: .  The new number is 66129853.
Mrs. Lee: OK. I’ll write a message for him.
David:   It’s really nice of you, Madam. Thank you very much. Goodbye!
Mrs. Lee:  Bye!

A. He’s not in at the moment. B. Who are you? C. My telephone number has changed. D. I’m not sure he would give me one or two. E. Could I speak to Bruce, please? F.I am very happy to hear that. G. Has he got your telephone number?