题目

小明和小华想探究一角硬币是由什么金属制成的，决定利用实验室器材测量一角硬币材料的密度。(1)小明选取了5枚相同的硬币，采用如图所示的方法测得硬币的直径为__________，再将5枚相同的一角硬币紧叠在一起用刻度尺测出总厚度，计算出硬币的总体积。然后，用天平测出这5枚硬币的总质量m，最后根据密度公式计算出硬币材料的密度，小明测得硬币的密度比真实值_______（选填“大”或“小”），简述理由_______________；(2)小华的测量步骤是：a．在选择下列单词或词组填入每句的空格中。每空格限填—词，每词只能填—次。A. bad B. Perhaps C. outdoor activity D. practise swimming E. in spring F. careful【1】Running is Mark's favourite ________.【2】Susan had a ________ cold. She went to see a doctor.【3】________ my son will be an astronaut in the future.【4】We ________ three times a week.【5】It's a good idea to have a picnic ________.【6】In London, traffic keeps to the left, so you should be ________.