商家对其葡萄进行减价促销活动，规定每天比前一天减价20%。某人在出售的第二天买了3千克，在出售的第三天又买了5千克，两次共花了42元，如果这8千克葡萄第四天买只要( )。

A．30.72元

B．31.64元

C．31.84元

D．32.08元

• A. Is that clear
• B. Can it do some washing
• C. Why do you think it is useful
• D. It appeared several centuries ago, didn’t it
• E. Will robots be the same as people
• F. What is it
• G. Could you please tell me more about robots
  A: Today we are going to talk about a great invention. It looks like a human being. (61)
  B: It’s a robot. (62)
  A: Of course not. The first robot was invented in 1921.
  B: (63)
  A: Sure. They can take the place of humans to do some boring work. They can also do a lot of dangerous work instead of humans.
  B: (64)
  A: No. Robots can do a lot of work instead of people in many ways, but people wouldn’t be replaced by robots. (65)
  B: We get it.