_______(safe)needstobeimprovedontherailwaysinthatcountry
产生感生电动势的非静电力是感生电场对电荷的作用力,产生动生电动势的非静电力是()
Goodparentshavetheabilitytocommunicatemessagesoflove,trust,andself-worth______theirchildren
Eachstudentistogiveashort___(speak)totherestoftheclassattheendofthesemester.
在研究刚体绕固定轴转动时,类似于牛顿第二定律F=Tna的规律是刚体绕固定轴转动的