题目

化学实验中常将溶液或试剂进行酸化或碱化，下列处理方法正确的是(    )A.检验C2H5Cl时，将C2H5Cl和NaOH溶液混合加热后，加入稀H2SO4进行酸化B.为了提高KMnO4溶液的氧化能力，用盐酸将KMnO4溶液进行酸化C.鉴定待测溶液中是否含有Fe2+时，用硝酸进行酸化D.进行乙醛银镜实验时，常在新配制的银氨溶液中滴入少量NaOH溶液Saturday morning was bright and fresh. There was a song in every heart, cheer on every face, and a spring in every step. Tom appeared with a bucket（桶）of white paint in one hand and a brush in the other. His Aunt Polly told him to paint the fence（篱笆）around the garden. It was ninety feet long and nine feet high. He felt very blue. Then he had a wonderful idea. He picked up his brush and started to work. Soon Ben came along the road. He was happily eating an apple. He stopped to look at Tom. Tom went on painting and pretended（假装）not to see Ben. “I’m going swimming,” said Ben. “Do you want to go swimming, Tom? But I guess you can’t. You have to stay and work, don’t you?”       “Work?” Tom said. “This isn’t work. I’m enjoying myself. Does a boy get a chance to paint a fence like this every day?” Ben thought about this. Tom continued painting carefully. Sometimes he stopped, stood back to look at the fence like an artist, and then added（增加）a bit more paint in just the right place. Ben was watching Tom paint with great interest. He was getting more and more eager（渴望的）to have a try himself. After a while, Ben asked Tom if he would let him paint a little. Tom thought about it, and said, “No, Ben, I can’t. You see. Aunt Polly wants it to be done well. Aunt Polly said that I must paint it with great care.” “Oh, please, Tom,” begged Ben. “I can do it. I’ll be really careful. Just let me try. I’ll give you half of my apple. Well, I’ll give you all of it!” “Well, all right, Ben,” said Tom. “You must be very careful.” He gave Ben his brush with worry on his face but joy in his heart. He sat down under the tree, and started to eat Ben’s apple. All day, boys came to make fun of Tom, but they ended up staying to paint. When Ben got tired, Billy was waiting. He gave Tom a kite for a chance to paint. Then Johnny offered him a basketball, and so on. By late afternoon Tom had got all kinds of toys, and the fence had got three coats of paint. Later Aunt Polly came to look at the painted fence. She was so pleased with Tom’s work that she gave Tom a large cake!1.Why did Tom pretend not to see Ben when he came and watched him painting?A.He saw Ben eating an apple happilyB.He tried to make Ben interested in itC.He didn’t want to go swimming with Ben at allD.He didn’t want Ben to share the chance to paint the fence2.What does the underlined word “spring” probably mean in Chinese?A.春天B.弹簧C.泉D.活力3.What do you think of Tom?A.HonestB.SmartC.ShyD.Stubborn