如图所示,轻杆一端固定了一小球,另一端安装在电动机的转轴O上.当电动机匀速转动时

题型:选择题

问题:

如图所示,轻杆一端固定了一小球,另一端安装在电动机的转轴O上.当电动机匀速转动时,小球在水平面内做匀速圆周运动.则

A.小球的加速度不变

B.小球所受合外力为零

C.小球所受合外力大小一定,方向改变

D.小球所受合外力大小、方向均一定

考点:匀速圆周运动
题型:选择题

阅读理解。

     I have a dream. One day in the year of 2008 when Beijing hosts the Olympic Games, I, an 18-year-old university student, am going to be a guide for many foreign athletes, news reporters and tourists. I'm going

to tell them many stories about China, a nation of 5,000 years of history. I am also going to tell them in

English about Beijing, a city of 3,000 years of history. So I am going to study harder from now on. I'm

going to speak English and write in English as much as I can. Do you want to have a dream like me?

判断正误,正确(T),错误(F)。

( )1. The writer is going to be an athlete when he is 18 years old.

(     )2. The writer is 18 years now.

(     )3. Many news reporters are going to Beijing for the Olympic Games.

(     )4. Beijing is a city of a long history which is 5000 years old.

(     )5. The writer wants to study harder at English for his dream.

题型:选择题

树脂PP指的是()。

A.聚氯乙烯

B.高密度聚乙烯

C.聚丙烯

D.聚苯乙烯

题型:选择题

中国人常说“五福临门”,下面哪一项是属于“五福”的()

A、品德高尚

B、子孙成群

题型:选择题

如果为了获得将所有因素结合在一起的优势,最好建立下列哪种类型的金融情报机构?()

A.行政型

B.执法型

C.司法型或诉讼型

D.混合型

题型:选择题

治疗霍乱首选为

A.抗菌药物
B.禁食
C.血管活性药
D.补液
E.抗毒素治疗

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