第17题: [单项选择]According to the passage parents and coaches should______. A. help children to win every game B. pay more attention to letting children enjoy sports C. enable children to understand the positive aspect of sports D. train children to cope with stress 参考答案:B 答案解析:依据为第三段第二行起的相关内容。
第18题: [单项选择]兆欧表输出的电压是()电压。 A. 直流 B. 正弦交流 C. 脉动的直流 D. 非正弦交流 参考答案:C