【明報專訊】"How would you like to trade that ice cream cone for my cube of sugar?" Oliver asked. "You wouldn't be interested in trading for this," Teddy answered. "I've been licking it." "That's not a problem," Oliver said. "I've been licking this sugar cube too." To trade for something is to barter (exchange) one thing for another. "The value of the things being traded should be relatively equal," Oliver noted.