题目

A、B两物体做简谐运动,在A物体振动20次的时间内,B物体振动15次,A、B两物体振动的周期之比为___________,频率之比为___________.若要求A、B都振动20次,需要的时间之比是___________. 答案：3∶4  4∶3  3∶4 解析:设t时间内A物体振动20次,则B物体振动15次,两周期之比=/=,又因为=,所以频率之比=.若A、B都振动20次,A所需的时间tA=20×TA,B所需要的时间tB=20×TB,所以==.Julia’s Chinese name is Liu Min.She is in Class 6 and her telephone number is 756－4321. She has a brother, his name is Adam. He is a tall boy, he has(有) some good friends at school. Julia and her brother like apples very much. Julia’s favourite colour is white, but Adam likes black. 黑色是他最爱的颜色. They are in China now, their Chinese teacher is Miss Wang. She is a good teacher.小题1:把第（1）句译成汉语。_____________________________________________________.小题2:把第（黑色是他最爱的颜色）句译成英语。____________________________________________________.回答问题。小题3:Who is their Chinese teacher? ____________________________________________________.小题4:What is Julia’s telephone number? ___________________________________________________.小题5:A  re Julia and Adam in China now?_____________________________________________________