设计与说理题所涉及的知识较多 ,综合性强 ,历来是考查学生知识技能、思维品质优劣的依据之一 .本文结合两例试题 ,说明这类题的解析方法 .例 1　给你一把刻度尺、细线和一个质量为 m的砝码 ,请你利用这些器材在实验桌上测出长约 1米的均匀直铁棒的质量 M.要求简述实验步骤 ,并 The knowledge involved in the design and theory problems is more and more comprehensive, and it has always been one of the criteria for examining students’ knowledge and skills, and the quality of thinking. This paper combines two examples to illustrate the analytical methods of such questions. Example 1 gives you a Use scales, fine lines, and a mass with a mass of m. Use these devices to measure the mass of a uniform straight iron rod about 1 meter long on the bench. M. Ask for a brief description of the experimental procedure and