【单选题】When perfectly competitive firms in an industry are earning positive economic profits,
A.
we would expect entry into the industry.
B.
we would expect stability in the industry, since it is in long run equilibrium.
C.
we would expect exit from the industry.
D.
we do not know whether there would tend to be entry, exit, or stability in the industry.
【判断题】银具有杀菌消毒的作用,用银制作餐具用于日常生活大有好处。
【判断题】不要带食物进实验室,不要随便乱动实验仪器。
【多选题】下列各组分子和离子中,几何结构全部为非直线形的一组是
【判断题】Task 1 Listen to the passage and decide whether the following statements are true (T) or false (F). 1. CMG Logistics Company is the leader in the transportation data services industry.