学习了第七章《粒子与宇宙》后，我们知道组成物体的分子很小，肉眼是看不见的，那么我们如何通过身边的器材来估测下分子的直径呢？在这里，我们来学习下用油膜法来估测分子的直径．实验步骤和原理如下：

（1）实验的研究对象是油酸分子，我们在实验前可以通过注射器测量出每一滴油滴的体积为7.5×10^﹣6cm³．

（2）把l滴该溶液滴入盛水的浅盘里，待水面稳定后，将玻璃板放在浅盘上，在玻璃板上描出油膜的轮廓．随后把玻璃板放在坐标纸上，其形状如图1所示．坐标纸中正方形方格的边长为2cm．我们可以数出轮廓内的方格数（格子未满半个的不计入各数，超过半个的算一格）

从而估测出这个油膜的面积是____ cm²．

（3）假设这层油膜是按如图2所示，由每个油酸分子紧密排列二组成的，则我们就可以估测出油膜分子的直径大约为____ cm．

下列图示的实验操作中正确的是(    )

    Years ago, I lived in a building in a large city. The building next door was only a few feet away from mine. There was a woman who lived there, whom I had never met, yet I could often see her sit by her window, sewing or reading.

    After several months, I began to notice that her window was dirty. Everything was unclear through the dirty window. I would say to myself, “I wonder why that woman doesn't clean her window. It really looks terrible.”

    One bright morning I decided to clean my flat, including the windows.

    Late in the afternoon when I finished the cleaning, I sat down by the window with a cup of coffee for a rest. What a surprise! The woman sitting by her window was clearly visible. Her window was clean!

    Then it dawned on me. I had been criticizing (批评) her dirty window, but all the time I was watching hers through my own dirty window.

    That was quite an important lesson for me. How often had I looked at and criticized others through the dirty window of my heart, through my own shortcomings?

    Since then, whenever I wanted to judge (评判) someone, I asked myself first, “Am I looking at him through my own dirty window?”

    Then I try to clean the window of my own world so that I may see the world about me more clearly.