如图所示,光滑的水平桌面上有一弹簧振子,弹簧的劲度系数为k。开始时,振子被拉到平

题型:选择题

问题:

如图所示,光滑的水平桌面上有一弹簧振子,弹簧的劲度系数为k。开始时,振子被拉到平衡位置O的右侧A处,此时拉力大小为F,然后轻轻释放振子,振子从初速度为零的状态开始向左运动,经过时间t后第一次到达平衡位置O处,此时振子的速度为v,则在这个过程中振子的平均速度为

[ ]

A.0            

B.v/2

C.F/(kt)        

D.不为零的某值,但由题设条件无法求出

考点:弹簧振子
题型:选择题

缺词填空。

     A Bag of Kindness "Boys and girls, tomorrow I want you to bring a cup of macaroni (通心粉) for our

craft class, OK?" These (1)w______  from my teacher rang in my mind all evening. I was afraid of the next

day

because I knew we had no macaroni at home. Living in an alcoholic (嗜酒的) family, we never had too

much of anything (2)e______ beer bottles.

     I went home after school. Where could I find macaroni? I knew that the local bottle shop gave ten cents

for a beer bottle, so I decided to sell some bottles to get money for macaroni.

     I started to (3)c______ the bottles. After selling those bottles, I earned eighty cents. Although I did my

(4)b______, I still had no macaroni for my craft class. "Weren't you (5)l______when I asked you to bring it,

John?" my teacher asked. I went red in the face. I didn't know what to say and other children started laughing.

Then a little girl, Rosalyn, who sat beside me turned to me and said,"You can have some of (6)m______."She

offered a bag of macaroni to me. The (7)k______ in her eyes made me cry and I ran out of the room.

     I (8)n ______ took her macaroni or thanked her for her bag of kindness. However, I often think about

Rosalyn and the way she turned to save me that day. I used to spend a great deal of my life complaining and

keep kind people like Rosalyn (9)a______. After that class, I (10)c______. I am grateful to all the people like

Rosalyn that made this world a better place to live in.

题型:选择题

设{an}是公比为q的等比数列,|q|>1,令bn=an+1(n=1,2,…),若数列{bn}有连续四项在集合{-53,-23,19,37,82}中,则6q=(    )。

题型:选择题

治疗量是指()

A.介于最小有效量与极量之间

B.大于极量

C.等于极量

D.大于最小有效量

E.等于最小有效量

题型:选择题

进入客户现场时,服务人员应统一着装、佩戴(),并主动表明身份、出示证件。协作人员应统一着装。

A.工号牌

B.安全帽

C.鞋套

D.工具包

题型:选择题

Pentium/Pentium Pro/Pentium Ⅱ的外部数据总线的条数为( )。

A.16

B.32

C.36

D.64

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