题目

If we _______ adequate preparations, the conference wouldn't have been so successful. A . haven't made B . wouldn't make C . didn't make D . hadn't made 答案：D在使用托盘天平测物体的质量时，下列说法中不正确的是 [　　] A．潮湿的物体和化学药品不能直接放在天平托盘里 B．增减砝码时只能用镊子夹取，且要轻拿轻放 C．称量物体质量时，为了使指针指在分度盘中央，可调节平衡螺母 D．被测物体的质量不能超过天平的称量