There was a famous church in London. It was 110 meters high. The center of the church was like a bell. The ceiling of the church was painted by a famous artist. A platform （平台）was built so that the artist could put up the ladder on it and paint the ceiling. The platform was about 70 meters over the ground.
    One day the artist was working hard and had nearly finished one popular corner of the ceiling. Also on the platform was his assistant, who was mixing paints. The artist stepped back so that he could see how his work was progressing. To have a better look at his painting, he stepped back again. Suddenly, his assistant shouted, picked up a small bowl of paint and started to paint the artist’s work on the top. The artist was very angry and rushed forwards to stop him.
    “What do you think you are doing?” he shouted angrily. “Are you mad?” His assistant replied, “I saw you walking backwards to have a better look at your painting. But you didn't notice that you had reached the very edge of the platform. You were in great danger. I wanted to make you move forwards. If I had not made you run forwards, you would have fallen backwards off the edge of the platform.

由欧姆定律的变形公式R= $\frac{U}{I}$ 可知，要测出导体的电阻，只需要用____测出导体两端的电压，用____测出通过导体的电流，代入公式就可以求出这个导体的电阻了．这种测量电阻的方法叫伏安法．

《旧唐书》称：武则天“制公卿之死命，擅王者之威力”（意为诛杀公卿，独断专权）。武则天遗言无字碑，由后人评价自己的功过。史学家之所以肯定武则天主要是因为（    ）

将下列中英文匹配。

⑴open the book____       A. 球

⑵close the window____    B. 坐下

⑶birthday____             C. 打开书

⑷ball ____                D. 生日

⑸Sit down____             E. 关窗

一个长方体的长与宽之比是5：2，宽与高之比是1：3，那么它的长、宽、高之比为(   )。