题目

My father ____ for Beijing on business tonight. A. is about to leave    B. has been leaving    C. is leaving   D. would leave 答案：C反应2X(g)+Y(g)  2Z(g)（正反应为放热），在不同温度（T1和T2）及压强（P1和P2）下，产物Z的物质的量n(Z)与反应时间t的关系如图所示，下述判断正确的是