题目

电磁打点计时器的电源应该是            （填“交流”或“直流”）电源。实验室使用我国民用电时，每隔            秒打一次点。   答案：解析:略 根据短文内容和首字母提示，在下文空格处填入适当的词使短文完整。在标有题号的横线上，完整写出空缺处所填单词的正确形式。（每空一词）Earth Hour started in Sydney on March 31，2007. O___1___ two million homes and businesses turned off their lights for an hour. A year 1ater，in 2008，Earth Hour became the w____2____ activity and was supported by millions of people from thirty-five countries. In 2009，more than two thousand cities in the world take part in it，and Earth Hour came to China. The purpose of the activity is to s____3____ energy and improve climate(气候). Earth Hour has brought about some great c__4__      to our lives.We may have different ways of s___5___ the hour. For example, we can go to school on foot or b___6___ bike，plant more trees, use water more than once，never leave the lights o_7___ when we are not at home. Try to make full use of paper by using b   8    sides.Earth Hour is a call for us to work together for a bright f   9    .  It is also a message of hope and action. Everyone can make a difference. It’s time for us to make our environment b_10__. Come on! Join us in Earth Hour 2011!