如图甲所示，一密闭的圆台形容器，内装一定质量的液体，如果把它倒置（如图乙），液体对容器底部的压力、压强的变化是（   ）

党的十八大报告指出，要毫不动摇地巩固和发展公有制经济，推行公有制多种实现形式。以下关于公有制的认识错误的是（   ）
①公有制是我国社会主义经济制度的基础 ②公有制经济就是生产资料和劳动产品归全体人民共同所有的经济 ③公有制经济和非公有制经济是完全对立的 ④现在我国公有制的实现形式还很单一 

自然界中的水都不是纯水，通过多种途径可以使水得到净化。下列方法得到的水最纯的是(    )

阅读下面短文，掌握其大意，然后从1~7 各题所给的三个或四个选项中，选出最佳选项。

There was once a farmer who lived near a road. It was not a1road, but from time to time, cars passed the farm.

Near the farm gate, there was a large 2 in the road. This hole was always full of water.

The drivers of the cars that passed by could not 3 how deep the hole was. They thought it was probably shallow (浅的). Then when they drove into the hole, they could not drive4because it was very deep.

The farmer did not spend much time5on his farm. He spent most of time watching the hole. When a car drove into it, he pulled the car out with his tractor (拖拉机) and demanded a lot of6 for doing this.

One day, a driver of a car said to him: “You must make a lot of money by pulling cars out of this hole7.”

“Oh, no,” the farmer said. “I don't pull cars out of the hole at night. At night I fill the hole with water.”