题目

﹣位学生要用托盘天平称量2.5g药品，在称量中发现指针向左偏转．这时他应该（ ） A．减少药品B．向右盘中加砝码C．移动游码D．调节天平的平衡螺母 答案：考点：称量器-托盘天平．. 专题：压轴实验题；常见仪器及化学实验基本操作． 分析：使用托盘天平称量药品时应遵循“左物右码”，称量指定质量的药品，此时先调好砝码和游码，再向左盘增减药品至天平平衡指针偏左，说明药品体质量大于砝码质量，应减少药品． 解答：解：用托盘天平称量2.5g请根据下面提示，写一篇短文。词数不少于50。     In your spoken English class, your teacher shows you the fol- lowing picture. You are asked to describe the picture and explain how you understand it. ______________________________________________________________________________________________________________________________________________________________________