A.5Px+0.1I-2.0Py，Py=2和Qx=10，那么x的交叉弹性为：B.-0.2C.-0.4D.-0.……

单项选择题假如Qx=20-0.5Px+0.1I-2.0Py，物品x和物品y为： A．替代品 B．互不相关 C．低档货 D．互补品

未分类题A．look upB．look downC．look awayD．lo0k back

未分类题听力原文：W: Hey! The train is late! I've been waiting her for ages.M: Which train, madam?W: The 8:18 to Baker Street.M: The 8:187 I'm afraid you've made a mistake, madam.W: A mistake? My timetable says: Baker Street train—8:18.M: Oh, no, madam. The Baker Street train leaves at 8: 08.W: At 8:08?M: You see, madam. They changed the timetable at the end of April.W: Changed it? May I see the new timetable? What does it say?M: It says: Baker Street train—8:08.W: Hm! So the train isn't late. I'm late.(13)A．Because the train was late.B．Because the train was canceled.C．Because she didn't know the timetable was changed.D．Because she was late.

单项选择题物品x的需求方程估计为：Qx=10-2Px+4I-Py，式中，I为人均收入，Py为另一物品的价格。这一方程说明： A．物品x是正常货，物品x和y不相关 B．物品x是低档货，物品x和y为互补品 C．物品x为正常货；物品x与y为互补品 D．物品x为正常货；物品x与y为替代品

单项选择题如果香港影星成龙上了意外事故保险后更多的表演高难度惊险动作，这种现象被称为( )。