下列不属于家庭节水行为的是（　　）

四项基本原则是____，改革开放是____。

Paul: Hey, Jenny, the subject for my school project is "Small invention that changed the world". Can you help me think of an invention?

Jenny: With ____! Let me think ... hmm ... I know! The zipper!

Paul: The zipper? Is it ____ such a great invention?

Jenny: Think about how often it's used in our ____ lives. You can see zippers on dresses, trousers, shoes, bags ... almost everywhere! I saw a website last week. The ____ of different inventions were listed there. For example, it mentioned that the zipper was ____ by Whitcomb Judson in 1893. But at that time, it wasn't used widely.

Paul: So when did it become popular?

Jenny: Around 1917.

根据汉语把英语句子补充完整。

质量为2.5t的小型载重汽车，额定功率为100kW，车上装有5t的砂石，已知汽车在平直公路上匀速行驶时所受阻力是汽车总重的0.2倍，汽车先以15m/s的速度在平直公路上匀速行驶到山坡底，消耗汽油2kg，然后又以额定功率行驶100s的时间，将砂石从坡底运送到50m高的坡顶施工现场（g=10N/kg），求：

①2kg的汽油完全燃烧放出多少热量？（汽油的热值取4.5×10⁷J/kg）

②汽车在平直公路上匀速行驶的功率为多少？

③汽车从坡底向坡顶运送砂石的机械效率是多少？