题目

如图所示，用水平拉力F拉上下表面水平、粗糙程度各处相同的物体A，使其在水平地面上匀速运动，当物体B静止不动时，与水平绳相连的弹簧测力计的示数不变．关于该状态，下列说法不正确的是(不计绳和弹簧测力计重)A．A对B的摩擦力为滑动摩擦力 B．B对A的摩擦力方向水平向左 C．B对A的摩擦力与水平拉力F的合力为零 D．弹簧测力计对B的拉力等于A对B的摩擦力The plan had been made to create a beautiful nature park with a large man-made lake on the outer parts of the city of Zhengzhou, the capital of Henan Province. However, thanks to a terrible trick played by nature, what the officials have ended up with, is a natural sandy mess!The government wanted to create a beautiful place where people of this busy industrial city could come to relax. But things did not quite turn out that way---shortly after digging up thousands of tons of sand, the underground water dried up. As a result, the dry sand has changed into a Sahara-like desert. While official reports show that the sand is piled up to 10 meters high, some people say that it is ten times more or about a 100-feet high in certain areas.If that is not bad enough, the sand hills that now spread across an area the size of four football fields, have influenced the environment. What’s worse is that on windy days, the dry sand moves into the city center, making it almost impossible to drive and forcing people to wear face masks and protective eyewear to prevent the sand from getting into their eyes, nose, and mouth.In an act of trying to keep the sand and provide the illusion(幻想) of green fields, the officials have even tried covering it with a green plastic netting. However, that has not done much to improve the terrible situation!As you can imagine, many of Zhengzhou’s residents are upset by the disaster. They think that desert wasteland that looks nothing like the green landscape they were promised, has resulted in polluting their pleasant city environment. Some think it is even stopping businessmen from coming to the city. 1.The author may agree that it is_________ to build a large man-made lake.A. possibleB. impossibleC. greatD. interesting2.The dry sand has changed into a Sahara-like desert because________.A. the weather in Zhengzhou is too dryB. there are enough trees in ZhengzhouC. they haven’t finished digging the lakeD. there is no underground water3.What kind of pollution have the sand hills caused?A. Light pollution. B. Water pollution.C. Air pollution. D. Sound pollution.4.What do Zhengzhou’s residents think of the man-made lake?A. Scary. B. Small.C. Helpful. D. Great.