4G卡普通客户需要进行二次补卡，需收取（）费用。
A.15元
B.30元
C.50元
D.0元
参考答案：A
一批零件，师傅单独加工需要12小时完成，徒弟每小时加工16个．现师徒两人同时加工，8小时完成任务．这批零件共有多少个？
Which of the following statements is least accurate with regard to the efficiency of monopolistic competition （）
A. Consumers benefit from brand name promotion and advertising.
B. Promotion and advertising enable consumers to make more informed decisions.
C. Monopolistic competition is at least as efficient as perfect competition.
