【单选题】乒乓球是我国人们最爱的运动项目之一,下列关于乒乓球受力及运动的说法中错误的是
A.
击打球的不同部位,球的旋转方向不同,表明力的作用效果与力的大小有关
B.
球在空中飞行时,如果不考虑空气阻力,则乒乓球只受重力作用
D.
运动的乒乓球在碰到桌面后会改变运动方向,表明力可以改变物体的运动状态
【简答题】阅读理解。 John lived in a big city with his wife and his two children. One Sunday afternoon, John took his yellow motorbike (摩托车) out of the room and was washing it when one of his friends came here. The ...
【单选题】在新中国的外交史上,用“小球推动大球”是指( )。
C.
用“乒乓外交”打开中日两国人民友好交往的大门
D.
用“乒乓外交”打开中美两国人民友好交往的大门
【简答题】Li Qiu is a boy of fif and studying in Grade Three at Oak school. His family lives outside the town. His parents have a farm and grow a lot of vegetables on it and they often sell them in the town...
【简答题】____是公务电话的核心,它实质上是一部由计算机软件控制的数字通信交换机,按用途可分为市话、长话和用户交换机。
【简答题】A:根据所给中文及句意,完成下列空格。(7分) The old man ____________ (刷) his dog’s fur every day. 2. Bill is very smart and he can always answer questions ______(正确地). 3. The girl is very young, but she can speak some ...
【单选题】在体育项目中称为我国的“国球”是什么球?( )
【单选题】乒乓球是我国的国球也是同学们喜爱的运动项目之一。下列说法中正确的是( )
B.
运动的乒乓球在碰到桌面后会改变运动方向,表明力可以改变物体的运动状态