题干

某研究性学习小组设计了如图Ⅰ所示的装置,探究空气中氧气的体积分数,其中A是底面积为5cm2、圆筒状玻璃容器(带密封盖),上面标有以cm为单位的刻度,B是带刻度的敞口玻璃管(其他辅助装置略).

他们的操作过程如下:

a.连接装置;

b.………;

c.加入水并调整B的高度,使A、B两侧液面相平,此时A中的液面于刻度15cm处;

d.将过量的白磷放在惰性电热板上,盖紧密封盖;

e.通电加热白磷至充分反应;

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同类题1

Complete the following passage with the words or phrases in the box. Each can be used only once. (将下列单词或词组填入空格。每空格限填一词,每词只能填一次)

A) youngest     B) professional     C) likely     D) grows up      E) won

    Each year, the news magazine Time For Kids selects several young people to serve as TFK kid reporters. These kids are not____ reporters, but they still have to interview some important people.

    Martin, who lives in New York, is a computer buff, plays the piano, and wants to be an airline pilot when he ____. When he got the assignment from TFK to interview Andrew Hsu, he wanted to talk about science. After all, Andrew had just become the____ winner of the Washington State Science and Engineering Fair. The 11-year-old scientist ____ the grand prize for identifying a particular genes that plays an important role in keeping the human body healthy.

F) free      G) meet      H) receive      I) also      J) improving

    Martin soon discovered that being a science whiz is just one of Andrew's achievements. He's ____an athlete who competes in swimming. But the main thing Andrew wanted to tell Martin about was the World Children Organization (WCO). Andrew started this organization along with his brother Patrick. This project is meant to help improve the lives of children.

    Andrew and Patrick believe that____education is the best way they can make a positive difference for children. They know that there are places where a ____education isn't available to kids. To help____that need, Andrew and Patrick had the idea of producing videos about science, math, and languages for children in countries where there aren't enough qualified teachers.