根据对话内容，从对话下边方框内的选项中选出能填入空白处的最佳选项，并将代表该选项的字母填入横线上。选项中有两项为多余选项。
A: What’s the date today
B: It’s June 16.
A: (16) Then it’s Dragon Boat Festival today, isn’t it
B: Yes. (17)
A: Did you have rice dumplings this morning
B: Sure. (18)
A: I didn’t.
B: What a pity! But I happen to have got some with me. (19)
A: I’d love to. By the way, why do you call it Dragon Boat, Festival
B: Because in China, people race dragon boats this day every year.
A: Oh, I see. (20)
B: Yon are welcome.
A．We Chinese usually eat rice dumplings this day.
B．I hate eating rice dumplings.
C．Thank you for your rice dumpling.
D．I don’t think so.
E．Would you like to have one
F．Already
G．How about you

[案例]
背景
某高速公路全长80km，路段上有6个互通立交，并有1.8km和2.1km的长隧道两座。根据提供的交通量，两个隧道都设计有通风、照明及隧道变电所，并有完整的监控系统及通信系统。该路设有一处监控分中心，能实现隧道变电所无人职守，能和省监控中心实现联网互传信息，以及为运营管理者提供信息。
[问题]

此路的监控系统具有哪些主要功能