摘要:25.如图所示.EF为绝缘水平面.O点左侧是粗糙的.右侧是光滑的.一轻质绝缘弹簧右端固定在墙壁上.左端与静止在O点.质量为m的不带电小物块A连接.弹簧处于原长状态.质量为2 m.电荷量为q的带正电物块B.在水平向右.电场强度为E的匀强电场作用下由C处从静止开始向右运动.B运动到O点时与物块A相碰(设碰撞时间极短.碰撞过程中无电荷量损失.A.B不粘连).碰后它们一起向右运动.当它们运动到D点时撤去电场.已知物块B与地面.EO段间的滑动摩擦力大小为0.2 Eq.物块B和A均可视为质点.弹簧的形变始终在弹性限度内.且CO=5L.OD=L.求: (1)撤去电场后弹簧的最大弹性势能, (2)返回运动的过程中.物块B由O点向左运动直到静止所用的时间.

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书面表达(共1小题,满分25分)

假如你是高中三年级的学生李华,你在学校组织了一项“有烦恼向谁说”的调查活动。请用英语给报社编辑写一封信,反映相关情况。内容包括:调查结果(如图所示)、持相应想法的理由及你对调查结果的看法。

注意:1. 信的开头和结尾已经给出。

2. 词数120词左右。

Dear Editor,

     I am a Senior Three student. Recently we have carried out a survey — “To whom do you do when in trouble?” The results are as follows.

                                                                     

                                                                     

                                                                    

                                                                     

                                                                    

                                                                    

                                                                      

                                                       Yours sincerely,

                                                              Li Hua

 

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书面表达(共1小题,满分25分)
假如你是高中三年级的学生李华,你在学校组织了一项“有烦恼向谁说”的调查活动。请用英语给报社编辑写一封信,反映相关情况。内容包括:调查结果(如图所示)、持相应想法的理由及你对调查结果的看法。

注意:1. 信的开头和结尾已经给出。
2. 词数120词左右。
Dear Editor,
I am a Senior Three student. Recently we have carried out a survey — “To whom do you do when in trouble?” The results are as follows.
                                                                     
                                                                    
                                                                    
                                                                     
                                                                    
                                                                    
                                                                      
Yours sincerely,
Li Hua

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