唐朝时发明的筒车,主要优势体现在( )
A:运用了自然力
B:可调节水的流量
C:可用于排涝
D:提高了耕作技术
如图所示,一轻质弹簧上端系于天花板上,一端挂一质量为m的小球,弹簧的劲度系数为k,将小球从弹簧为自由长度时的竖直位置放手后,小球做简谐运动,则:
①客观事物的本质会随着人们认识的变化而改变
②人的认识是主体与客体相互作用的过程和结果
③追求终极真理是人类探索自然奥秘的根本目的
④通过认识个别事物能够达到对世界整体的把握
I am a middle-school student. Now let 1 tell you something 2 our classroom. It's very 3 There are two maps4 the back wall. 5is a map of China.6 is a map of the world (世界).There are7 desks and chairs in our classroom. There is a big desk 8 theteacher in the front of it. We 9 four classes in the 10 and two in the afternoon