如图所示,是某同学站在力板传感器上,做下蹲-起立的动作时记录的力随时间变化的图线

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问题:

如图所示,是某同学站在力板传感器上,做下蹲-起立的动作时记录的力随时间变化的图线,纵坐标为力(单位为牛顿),横坐标为时间。由图线可知,该同学的体重约为650N,除此以外,还可以得到以下信息(   )

A.该同学做了两次下蹲-起立的动作

B.该同学做了一次下蹲-起立的动作,且下蹲后约2s起立

C.下蹲过程中人处于失重状态

D.下蹲过程中先处于超重状态后处于失重状态

考点:牛顿第二定律
题型:选择题

阅读短文,根据短文内容及首字母提示,在空白处填入一个适当的单词。

     Reading is an activity people enjoy a lot in their free time.

     Some like reading newspapers and (1) o________ enjoy novels or comic (喜剧的) books. My

(2) f__________books are those about the lives of great people. Reading them always gives me a

lot of ideas on how to make my (3) o________ life better.

     Great people are remembered not because they were handsome or beautiful, but because they

did not give up (4)w________ their lives were difficult. They tried to use (5) e________ chance

to change their lives and make the world better.

     One good example is Orville and Wilbur Wright, the two brothers (6) w_______ invented the

airplane. The plane has (7) m________ the world into a small village. Hard work, not good luck,

is the (8) r________ why the Wright Brothers could invent this convenient (方便的) machine and

become great people. Today we will remember them when we see planes (9) i________ the sky.

     Whenever I read (10) s________ about great people, I always learn a lot from them and they

encourage me to march on.

     This is why I enjoy reading about great people's lives.

题型:选择题

饮食、饮水中缺少哪种物质可引起地方性甲状腺肿大?(  )

A.钙

B.铁

C.维生素B1

D.碘

题型:选择题

关于基础代谢影响因素的叙述,正确的是()。

A.瘦高者基础代谢低于矮胖者

B.体表面积大者基础代谢低于体表面积小者

C.男性基础代谢高于女性

D.老年人基础代谢高于年轻人

E.孕妇、儿童基础代谢相对较低

题型:选择题

机械加工中常用的刀具材料有:碳素工具钢、高速钢、硬质合金和()

A.高碳钢

B.低碳钢

C.合金工具钢

D.不锈钢

题型:选择题

在多相体系中,被分散的物质叫做()

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