题目

PM2.5是指大气中直径接近于2.5×10－6 m的颗粒物，下列有关PM2.5说法不正确的是( ) A．PM2.5表面积大，能吸附大量的有毒、有害物质 B．PM2.5在空气中形成气溶胶 C．实施绿化工程，可以有效地防治PM2.5污染 D．研制开发燃料电池汽车，降低机动车尾气污染，在某种程度上可以减少PM2.5污染 答案：答案 B 解析 胶体分散质粒子的直径大小在1～100 nm之间,而PM2.5的颗粒物的直径接近于2 500 nm,B错误。阅读理解。     My grandfather was a fine man. I loved him very much. But one day I told him a lie (谎话). I can not tellyou now what the lie was. I was only seven years old then.     Grandfather was not cross with me.      "Ask Jim to get a long ladder," he said. "My boy now jumps from the tops of houses, up to the roof(屋顶)."      Jim brought the big ladder. Then Grandfather said,"My boy now jumps from the tops of houses. The ladderis for him."     I knew at once what he was telling me. I had often heard the old saying, "A lie is a jump from the top of ahouse."      I said nothing. But I felt like crying.     The minutes went by. What would people think about the ladder? It stood by the front door. I was afraid itmight be there a long time. I had to do something!    At last I went to Grandfather. He was reading a book. I went up to him and put my face on his arm.     "Grandfather," I said, "I will not tell a lie again. We don't need the ladder now." Grandfather seemed very happy once again. He called Jim. "Take the ladder away," he said. "My boy does not jump from the tops ofhouses."     His words made me happy once again. 1. From the passage we can not know ______. [     ]A. whether the boy told a lie B. what the lie was C. what Grandfather did with the boy D. how the story ended 2. The word "cross" in the story means           . [     ]A. angry B. surprised C. happy D. kind 3. Grandfather asked Jim to get a ladder to ______. [     ]A. see whether the boy could jump from the top of a house B. help the boy to climb to the top of the house C. let the boy know it was wrong to tell a lie D. make the boy cry 4. "What would people think about the ladder?" shows the boy was afraid people would ______. [     ]A. know what had happened B. take the ladder away C. come to learn the roof D. come to take care of Grandfather 5. At the end of the story the result is ______. [     ]A. enjoyable B. sad C. not clear D. untrue