题目

图中的四个实例，目的是减小摩擦的是（ ）A．鞋底的花纹B．浴室脚垫做得凹凸不平C．在合页轴上加润滑油D．矿泉水瓶盖上的条纹 答案：【答案】C【解析】鞋底有凹凸的花纹，是在压力一定时，增大接触面的粗糙程度来增大鞋和地面之间的摩擦力，防止滑倒，A不符合题意；浴室脚垫做得凹凸不平，是在压力一定时，增大接触面的粗糙程度来增大脚和脚垫之间的摩擦力，防止滑倒，B不符合题意；在合页轴上加润滑油，使相互接触的两表     Volunteers, as an essential part of a successful world exposition, are a major channel for the public to participate in, serve and share the world exposition and a means to showcase the image of the host country and city．The following information is about the volunteer for the World Exposition 2010 Shanghai China. I．Basic Requirements for Volunteers l         Be willing to participate in voluntary services of Expo 2010; l         Age limit: Expo Site volunteers must be born before April 30, 1992 and Expo City Voluntary Service Station volunteers before April 30, 1994; l         Obey the laws and regulations of the PRC; l         Be able to participate in training and relevant activities before the opening of Expo 2010; l         Possess necessary knowledge and skills needed by the position; l         Be in good health to meet the requirements of corresponding voluntary positions. II．Further Information for Volunteers l         Source Residents of Chinese mainland, Hong Kong, Macau and Taiwan, as well as overseas Chinese, and foreigners can all apply to be the volunteers. l         Signup methods Applicants may log in onto the official websites for online signup．They may also consult or connect with the Expo Volunteer Stations． l         Time May 1 – December 31, 2009 III．Volunteer Training 　　Volunteer training includes general training, special training and position training．General training is carried out through internet, while special training and position training are provided through classroom lectures and field practice． IV．Volunteer Types l         Expo Site volunteers refer to those offering voluntary services to visitors and the Organizer in the Expo Site, mainly including information, visitor flow management, reception, translation and interpretation, assistance for the disabled, and assistance in media service, event and conference organization and volunteer management. l         Information booth volunteers are stationed in the Expo’s information booths at key transportation centers, commercial outlets, tourist attractions, restaurants, hotels and cultural event places outside the Expo Site．They offer services including information, translation, interpretation and even first aid. 1．According to the passage, which one is NOT true?        A．If you were born in April 1993, you can be a volunteer in Expo City        B．If you were born in April 1991, you can be a volunteer in Expo Site.        C．Volunteers of the World Exposition should obey the laws and regulations of the PRC.        D．Applicants may log in onto the official websites for online signup. 2．Volunteers of the World Exposition 2010 Shanghai China have been trained well．Which of the following doesn’t belong to the Volunteer training ?        A．Position training.                                  B．General training.          C．Internet training.                                  D．Special training.   3．Which of the following services is offered by information booth volunteers?        A．Visitor flow management.                     B．Helping the disabled.        C．Assistance in media service.                  D．Emergency First aid．