题目

下列物质中硬度最大的是（    ） A.石墨             B.铁             C.金刚石           D.石灰石 答案：思路解析：因为用金刚石做成的玻璃刀，可以切割大理石，加工坚硬的金属，可推出选项B、D不正确；我们用的铅笔芯就是用石墨制作的，故质软，选项A也不正确；只有金刚石是天然存在的最硬的物质，故其硬度最大。 答案：C11. Chinese athletes have also made important c______ to the Olympic Games. 12.Some of the Olympic athletes who have brought joy to people across the world with their a______ to push the boundaries of human achievement. 13.Better finish your work before watching TV.______ (否则)you’ll have to stay up late. 14.I am delighted to have been invited to your school to talk to you about the history and s_______ of the Olympic Games. 15.Mr. Smith will be in charge of the business during my father’s a__________. 16.He likes drinking so much. It is u__________ for him to refuse a drink today, totally out of my expectation. 17.Joe was celebrating his success with his colleagues. _________（与此同时）, his father was waiting for him at home. 18. Some old customs that were not matched with the reality have been ________ (移除). 19. In fact, Australia is the only country that is also a __________ (大陆). 20. His lecture is on ___________ (当代的) American novelists.