题目

To make members of a team perform better，the trainer first of all has to know their      and weaknesses． A．strengths         B．benefits          C．techniques              D．values 答案：A 解析: strengths and weaknesses优点和缺点, benefit n.益处, 好处；technique n.技巧, 手法, 技术；value n.价值, 价格。声音在15℃空气中的传播速度是340m/s，传播170m距离所需的时间为    s．