单项选择题
What is main purpose of the passage（）
A．To outline contrasting types of economy. B．To explain the science of economics. C．To argue for the superiority of one economics. D．To compare barter and money exchange markets.
单项选择题 Which of the following is the best title for passage（）
单项选择题 Which of the following is the main purpose of this announcement（）
填空题 A．pension B．mission C．procession D．occasion
