①地势西高东低②以外河流为主③呈阶梯状分布

④我国山区面积占全国总面积的1/3  ⑤地形复杂多样 ⑥山区面积广大

选择合适的答案

①Did they go home by bike ?  ____            

②Where did you go yesterday ?  ____            

③What did you see ?   ____                    

④ Did you see a bus yesterday ?  ____           

⑤ When did your father come back ?  ____       

⑥ Do you live in London, too ?   ____          

⑦Did John eat rice yesterday ?   ____            

⑧How did you go home yesterday ?____           

⑨When did you come back ?   ____              

⑩What did she do yesterday ?  ____              

A No, I didn’t.   B Yes, he did .   C I went to the park .    D Yes, I do .

E I came back last Friday.   F No , they didn’t.    G We went home by bus .

H I saw lots of places .    I She watched TV.    J He came back last Sunday.

如图所示，已知半径分别为R和r（R＞r）的甲、乙两个光滑的圆形轨道安置在同一竖直平面上，甲轨道左侧又连接一个光滑的轨道，两圆形轨道之间由一条水平轨道CD相连．一小球自某一高度由静止滑下，先滑上甲轨道，通过动摩擦因数为μ的CD段，又滑上乙轨道，最后离开圆轨道．若小球在两圆轨道的最高点对轨道压力都恰好为零．试求：

实验器材如图所示：一个电源，L₁、L₂两个完全相同的灯泡，A₁、A₂两个电流表，一个开关，若干条导线．请你设计一个电路，要求：两个灯泡L₁、L₂并联；两个电流表接入电路，且A₁的示数大于A₂的示数．