如图所示，在0≤x≤ $\sqrt{3}$ a，0≤y≤a的长方形区域有垂直于xoy平面向外的匀强磁场，磁感应强度大小为B，坐标原点O处有一个粒子源，在某时刻发射大量质量为m、电荷量为q的带正电粒子（重力不计），它们的速度方向均在xoy平面内的第一象限，且与y轴正方向的夹角分布在0～90°范围内，速度大小不同，且满足 $\frac{2qBa}{m}$ ≤v≤ $\frac{3qBa}{m}$ ，已知粒子在磁场中做圆周运动的周期为T，则下列说法正确的是（   ）

某市举行“希望杯”足球比赛，由全市的6支企业职工业余足球队参加，比赛组委会规定：比赛采用单循环制进行，每个队胜一场得3分，平一场得1分，负一场得0分．在今年即将举行的“希望杯”足球比赛中，参加比赛的市工商银行队可能的积分值有（　　）

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    The day finally came，when I had to leave the warm home where I'd grown up.I ran to the back yard，as tears came up from my heart.Suddenly I1a hand rest on my shoulder.I looked up to2mygrandfather.“It isn't3，isit，Billy？”he said softly.

    Gently4myhand in his，we walked，hand in hand，tothe front yard，5a hugered rose­bush sat alone.

    “What do you see here，Billy？” he asked.I looked at the flowers，not knowing6to say，and then answered，“I see something soft and7，grandpa.”

    He pulled me8.“It isn't just the roses that are beautiful，Billy.It's that special place in your heart that makes them so.”“Billy，I9these roses when my first son was born.It was my10of saying 'thank you' to God.I11to watch him pick roses for his mother. Then, as a young man of only 20，a terrible war robbed him of his life.” Grandpa slowly stood up.“Never say good­bye，Billy. Never12to the sadness and the loneliness.Instead，I want you to remember the joy and the13when you first said hello to a friend.”

    A year later，my grandpa became very14.Then all members of the family were15back，and I returned to the old house. When it came to my16，I took his hand as17as  he had once taken mine.

    “Hello，grandpa，”I18.His eyes slowly opened and said，“Hello，my friend.” With a brief19he died. Suddenly，and truly.I knew what he had20about never saying good­bye—about refusing to give in to sadness.​