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问题 不定项选择

一个物体以4m/s的线速度做匀速圆周运动，转动周期为2s。则该物体在运动过程的任一时刻，速度变化率的大小为[ ]

A．2m/s2

B．4m/s2

C．0

D．4πm/s2

答案

答案：D

改错题

以下文中共有10处语言错误，每行最多有两处。错误涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏词符号（∧），并在其下面写出该加的词。删除：把多余的词用斜线（﹨）划掉。修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1.每处错误及修改均仅限一词；2.只允许修改10处，多者（从第11处起）不计分。

The summer holiday，when I’m looking forward to, is coming. What a fun it is to go swimming! Playing football is one of my hobby. I can ride my bicycle，climb high mountains, or go fishing. Sometime I can play chess with Grandfather. How interested my holiday will be! But my father is always afraid whether I will hurt by a truck, fall into water, fell off a tree or something else. And also he is afraid whether I will fight against others or be taken by bad people. And if I’m careful and polite enough，how will these things happen？I must try best to persuade my father.
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单项选择题

注灰塞配制灰浆时，理想的水温是（）。

A、10～20℃

B、20～30℃

C、30～40℃

D、40～50℃
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