题目

I was on a business trip then, otherwise I to the hospital for tests. A . went B . had gone C . would have gone D . would go 答案：C 如图所示，一倾角为45°的斜面固定于竖直墙上，为使一光滑匀质铁球静止，需加一水平力F，若力F过球心，下列说法中正确的是（                                                                                    ）                                                                                                                                     　   A．  球一定受墙的弹力且水平向左 　   B．  球可能受墙的弹力且水平向左 　   C．  球一定受斜面的弹力且垂直斜面向上 　   D．  球一定同时受到墙的弹力和斜面的弹力