沿水流方向升高的管线，如长度较大，应在管线（）设空气阀，形成良好的排气条件。
A.起点
B.末端
C.中间
D.拐点
参考答案：B
________volcanoes now for many years, I am still as enthusiastic about my job as the first day I first______.
A．Studied, started
B．Have studied, started
C．Having studied, started
D．Having studied, starting
甲、乙两车分别从A、B两地同时相向而行，已知甲车速度与乙车速度之比为4：3，C地在A、B之间，甲、乙两车到达C地的时间分别是上午8点和下午3点，问甲、乙两车相遇是什么时间？
