题目

用托盘天平测量铜块质量时，应将天平放在  ▲    桌面上，游码移到标尺的零刻度处，若天平的指针静止在图甲所示位置，则可将平衡螺母向  ▲  （选填“左”或“右”）调节，使天平平衡．测量中，当右盘所加砝码和游码位置如图乙所示时天平平衡，则该铜块的质量为  ▲  g．     答案：水平  右  52.4 解析:略  If you have a problem _____ your composition, you had better ask your teacher ______. A. in; on some advice B. for; for some advices C. on; some advice D. with; for some advice