题目

 [2016·天津卷] 电磁缓速器是应用于车辆上以提高运行安全性的辅助制动装置，其工作原理是利用电磁阻尼作用减缓车辆的速度．电磁阻尼作用可以借助如下模型讨论：如图1­所示，将形状相同的两根平行且足够长的铝条固定在光滑斜面上，斜面与水平方向夹角为θ.一质量为m的条形磁铁滑入两铝条间，恰好匀速穿过，穿过时磁铁两端面与两铝条的间距始终保持恒定，其引起电磁感应的效果与磁铁不动、铝条相对磁铁运动相同．磁铁端面是边长为d的正 根据表格内容，选择正确答案。 1.On Sunday, the zoo opens at ______. A．10: 00 in the morning                    B．8:00 in the morning C．6:00 in the afternoon                    D．8:00 in the afternoon 2.The zoo opens ______ days a week. A．one              B．two              C．five              D．seven 3.If you are 13 years old. You want to go to the zoo, you should pay _____. A．$ 3              B．$ 6               C．$ 8              D．free 4.Kate is 12, and her little sister is 6. If they go to the zoo, they should pay ___. A．$ 9              B．$ 6               C．$ 11             D．$ 3 5.The zoo closes at ______ on Wednesday. A．10: 00 a.m.        B．8:00 a.m.          C．6:00 p.m.          D．8:00 p.m.