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问题 选择题

下列各量：①密度 ②浮力 ③风速 ④温度，其中是向量的个数有（　　）个．

A．1

B．3

C．2

D．4

答案

根据向量的定义，知道需要同时具有大小和方向两个要素才是向量，

在所给的四个量中，密度只有大小，浮力既有大小又有方向，

风速既有大小又有方向，温度只有大小没有方向

综上可知向量的个数是2个，

故选C．

完形填空
根据下列短文内容，在短文后的空格处填上一个恰当的词，使短文完整、通顺。
much ,  arm ,  wait,  see,  when ,  spend,  she,  worry ,  have ,  grow
Only Mother Love is true love. It gives everybody everything all his life. ­­­­小题1:__you are still a baby, mother takes good care of you as much as possible . In your waking hours she always holds you in her  小题2:. When you are ill, she stops her work right now to look after you day and night and forgets about  小题3:  . When you are小题4:   up day by day, she feels very happy. When you are old enough to go to school, mother still looks after you all the time. On cold winter days, she always tells you to put on  小题5: clothes . She always stands in the wind小题6:     for you back from school. When you hurry  to leave home for school with little breakfast, she always feels 小题7: about you at home. She usually knows about your study and 小题8: much money on your school things. When you do well at school, the brightest smile will be 小题9:   on her face.
Mother is always ready to give everything she 小题10: to her children,  not to receive . What true love that is in the world! We will remember Mother Love for ever.
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填空题

某同学郊游时，用半小时走完2km的路程，休息半小时后，再用30 min走完2.5km的路程．那么，他在前半小时的平均速度是______km/h，中间半小时的平均速度是______km/h，后30 min的平均速度是______km/h，全程的平均速度是______m/s（最后一空保留两位有效数字）．
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