— Only five dollars. It's very cheap.
A: What time is it
B: How much do you want
C: How much is it
D: What's wrong
请阐述雅典民主政治的范围、三个阶段和性质,并客观评价雅典的民主制度。
如图所示,水平桌面上有一只装满水的溢水杯,水深为20 cm;一只底面积48cm2,高度10cm,质量为80g的接水杯。现将弹簧测力计挂着重为10 N的物块,缓缓浸入溢水杯中的水里,直至浸没,溢出水的质量为 0.4 kg.物块浸没在水中后,求: