Harry had a very small farm. He only had one cow but dreamed about having a large farm. He once asked his father Bill, “I'd like to have that land over there. How can I get it?” His father encouraged him to go and talk to the landowner(地主) to see how they could get the land. Harry said. “But we don't have enough money.” His father said, “Don't worry. Go and talk to him.”
Several years passed. Harry had not only the land, but also several hundred cows. He had a happy life with his wife. Later, Harry's wife, Sarah, had a dream. “I want to build the biggest farm in the world.” She said. They called their friend Manuel about this task. Three days later Manuel had a plan for the whole project. Then they asked, “How much will it cost?” Manuel said they needed a lot of money. “Nobody will lend us so much money to build a farm,” they thought. But the manager of the bank trusted them and their dream. A few months later, La manuel, the biggest farm in the world, was opened.
为石墨电极；
为铁电极；
为铝电极（已除去表面氧化膜）；
为多孔石墨电极，烧杯中是足量饱和食盐水（滴有酚酞），连好导线后，电流计指针发生明显偏转。下列判断正确的是
