题目

While Tom and Mary were on holidays at the seaside, they enjoyed _____1____ the seagulls. They _____2____ a lot about these lovely birds. They will often come close to you on the beach when they are eating something. If you _____3____ a piece of bread to them, they will soon catch it. Seagulls swim well, but they don’t often dive for fish. They are also good at flying _____4_____ their large wings. When a seagull is flying, he puts his legs _____5____ his body. Tom often watched them _____6____ close to the ground because he liked the way they _____7____ the air with their wings and 【2016年甘肃省张掖市】如图为干电池的结构示意图．请利用所学知识完成下列问题．（1）碳棒（主要成分是石墨）用作干电池的正极是利用了石墨的__________性．（2）干电池的材料很多可以回收利用．例如双氧水与回收的二氧化锰可用于实验室制取氧气，请写出反应的化学方程式__________．（3）黄铜是铜与锌的合金，其硬度__________（填“大于”或“小于”）纯铜。将足量的锌片放入硫酸铜溶液中，观察到__________的现象，说明锌比铜活泼。