题目

某化学兴趣小组同学用如图装置测定空气里氧气的含量，待镁条熄灭并冷却后，打开弹簧夹，集气瓶中事先放少量细沙的目的是__⑴__ 【提出问题】利用镁条在空气中燃烧的原理,测定空气里氧气的含量是否合理？ 【数据分析】如果镁条只和空气中的氧气反应,则进入集气瓶中水的体积最多不超过其容积的_⑵__%，现进入集气瓶中水的体积约为其容积的70%，已确认本实验的操作过程正确、规范.根据空气的组成可推出除了氧气，减少的气体中一定还有__⑶___Hi, my name is Amy. I am a Grade 7 student, and I would like to tell you something about my class and myself. There are ten classes in Grade 7.In each class, there are about forty students. I think that my class, Class 4 is the best(最好的).That is because all the students in my class work very hard and the teachers are all very nice to the students. But I am not one of the best students in the class. I love reading, and I am very good at Chinese and English. I don’t find Maths very interesting, so I am not good at it. I want to work hard at it. My teacher, classmates and my parents would like to help me with my Maths.【小题1】How many classes are there in Grade 7at Amy’s school?A．Six B．Seven C．Nine D．Ten 【小题2】How many students are there in Grade 7?A．About 400. B．About 500 C．About 300 D．About 600 【小题3】Why is Amy’s class the best class in Grade 7? A．Because the teachers are the best. B．Because the boys work very hard. C．Because the students are very nice to the students. D．Because the students work very hard and the teachers are very nice. 【小题4】What does Amy love doing?A．Singing B．Reading C．Swimming D．Watching TV 【小题5】What is Amy not good at?A．Chinese B．P.E. C．English D．Maths