题干

现有白纸,溶质质量分数分别为:A、10%的NaOH溶液;B、5%的硫酸溶液;C、5%的紫色石蕊试液。试设计出《“雨”落叶出红花开》的趣味实验:先在白纸上用玻璃棒蘸取____(填编号,下同)画上花,再蘸____画上叶,将白纸挂上墙,用____向纸上喷洒即可,实验的化学原理是____

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答案(点此获取答案解析)

B,A,C,紫色石蕊试液遇酸变红、遇碱变蓝

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根据短文内容, 从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    Have you ever heard of homecoming? It's a tradition celebrated every year in the US. At homecoming, a school or university welcomes back former students or alumni(校友).____It means, “coming home.”

    This is a time when everyone can get together.____There are events that encourage school spirit all throughout homecoming week, which leads to the big day on Friday.

    A major activity that most students will take part in is choosing the homecoming king and queen.____ This is a group of boys and girls who represent (代表) school spirit. At the end of the week, students vote for a boy and a girl to be the king and the queen.

    Then it's time for the football game, the main event of homecoming week! ____Almost everyone from school goes to the game: students, parents, teachers, and alumni visitors. If they win, everyone is very happy.

    ____ Students dress up, and some might even bring a date to go with them. After the dance, homecoming is officially over, and everyone can't wait for next year!

A. The last event is the homecoming dance.

B. That is where the name comes from.

C. Students get to pick who will be on homecoming court early in the week.

D. The tradition began more than 100 years ago in the United States.

E. The football team faces a lot of pressure to do well for the big crowd.

F. Homecoming usually lasts a week and happens in the fall.

G. Homecoming week was not just about fun, but also a chance to try out new things.