题干

已知:白磷的着火点为40℃,红磷的着火点为240℃,五氧化二磷会刺激人的呼吸道.为了探究燃烧的条件,小军设计了如图所示的实验装置(夹持仪器略去).

实验过程:①通入N2,点燃酒精灯,一段时间后,a、b中均无明显现象;②熄灭酒精灯.立即改通O2,a中无明显现象,b中红磷燃烧.

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阅读下面短文,从短文后各题所给的四个选项(A、 B 、C 、D)中,选出可以填入空白处的最佳选项。

    Annie, my neighbor's daughter, was away for her first term at college this year. She is a very sweet girl but just a bit shy. When her birthday month 1, I found out she was feeling a bit blue and 2.

    Her family is quite 3 and finances are tight, so there wouldn't be any birthday visitors.

    I wanted to send her a card and maybe a small gift to 4 her up. I got her school address from her mom and planned to 5 send her something. Then I got a(n) 6!  I thought perhaps I could give her a big 7. I bought some balloons, birthday hats and other small novelties (新奇玩意) at a one-dollar 8.  I took a small 9 and asked three other people in my area to sing Happy Birthday and send some birthday 10 to her. Other people found out 11 we were doing and added their voices, 12 it really sounded like we had a party 13 .

    Then I bought her a small present and a card as 14 originally. The real fun was 15 it to be sent. I arranged everything specially so it was like opening a birthday present!

    At the last minute, I added a pack of small cakes and a box of birthday 16 before sending it off. 

    I got a call a few days later. Annie said her roommate and one of her neighbors in her school got together with her and held the party for her once it arrived. She sounded so 17 and I was so glad that she had some friends to 18 her special day with her.

    It was such an easy and fun thing to do. The people who helped me make the tape still laughed and talked about the 19 experience. And Annie told me it was the most fun birthday she can 20!