语文课代表因病请假休息,语文老师指派孟杰同学临时代替语文课代表职责。孟杰同学尽管不大愿意,但还是答应了;并且,他做得很认真,甚至比语文课代表做得更好,受到语文老师的表扬。这说明( )
①不是自愿选择的责任,人人都能做好
②不管是自愿选择的责任还是非自愿选择的责任,都应该无悔地承担
③即使不是自愿选择的责任,只要全身心地投入,也能够做得出色
④承担不是自愿选择的责任,往往比承担自愿选择的责任做得好
A:①③
B:①②
C:②③
D:③④
take your kite tomorrow?
My parents want to take me to visit Beijing this summer holiday. I want to plan a good trip. So I must learn something about Beijing on the Internet. Beijing is a beautiful city. Autumn is the best season. There are many places of interest in Beijing. We want to visit the Great Wall, the Palace Museum and the Summer Palace. Beijing Duck is very famous all over the world. I hope I could have a try.
We can get to Beijing by train. I want to buy a gift for my good friend. I also want to send a postcard to my teacher. I think I will have a great holiday.
右侧宣言指导的是( )
如图所示,弹簧左端固定在O点的墙上,另一端与一质量为m=4kg的物体接触但不连接,弹簧处于压缩状态.现将物体由静止释放,物体在弹簧弹力作用下沿水平轨道向右运动,运动到A点时,物体已完全脱离弹簧,速度vA=5m/s;运动到B点时,速度为零.已知轨道OA段光滑,AB段粗糙,A、B之间的距离l=5m,求: