有几位同学在学校用“IC”卡打电话时，议论起电话交换机，他们有以下几种说法，其中正确的是（）

某同学在“探究浮力大小与哪些因素有关”的实验中：

某校高二(5)班全体同学发起倡议，就“马克思主义哲学与建设中国特色社会主义”为主题进行探究。回答以下问题。

    This is Kate Smith. She is 13 years old. She lives in Guangzhou. She studies in No.10 Middle school. Her parents work there. They are both English teachers. They are form the UK. She likes eating junk food. She doesn't like playing sports. She has one healthy habit: She sleeps for 9 hours every night.
    Kate Smith has a brother. His name is Jack Smith. He is 11 years old. He doesn't eat junk food. He likes playing sports. He often runs, plays basketball, and goes swimming. He eats fruit every day. He likes eating vegetables. But he has an unhealthy habit: He sleeps for 6 hours every night.