A、$60. B、$50. C、$40. D、$10. C这是一道计算题，问双人间的价格是多少。根据对话内容，房间原价是50美元，这个月可以享受八折优惠，因此房间的实际价格是40美元。注意20% discount的意思是“八折”。

W: Hello, may I help you?
M: Yes, I’d like to book a room for tomorrow.
W: Which kind of room do you prefer, sir?
M: A double room.How much is it?
W: A standard double room is $50 per night.But we offer 20% discount this month.
M: Oh, that’s great.How about the environment?
W: It’s very comfortable, with a view of the sea.
M: OK, I’ll take it.My name is Martin.
W: OK, Mr.Martin.See you tomorrow.
M: Thank you.Bye!
8.Which kind of room does the man want to book?
9.How much is the double room?
10.How is the living environment of the room?