【判断题】普通二极管管体上有白色(或者是黑色)环形标志的一边为负极( )
【单选题】---Good morning. I’ve got an appointment with Mr Smith in his office. ---Morning. You ________ be Mr Jones. This way, please.
【判断题】Some students take a year off their studies to become travel agents.
【单选题】四冲程发动机一个工作循环曲轴旋转2周,凸轮轴旋转:
【简答题】选择江河取水构筑物位置时应考虑哪些因素?分析下图中取水口选在哪个点合适,说明原因。