关于通电导线所受安培力F的方向,磁场B的方向和电流I的方向之间的关系,下列说法正确的是( )A.F、B、I三者必须保持相互垂直B.F必须垂直B、I,但B、I可以不相互垂直C.B必须垂直F、I,但F、I可以不相互垂直D.I必须垂直F、B,但F、B可以不相互垂直
An actor is usually a _____. A. man B. woman C. police
Amy is a teacher, she _____ English. A. teach B. teaches C. teacher
Chen Jie likes ____ a bike. A. ride B. riding C. rides
What _____ she like to do? A. do B. does C. is
Where does the ____come from ? It comes from the clouds. A. rain B. sun C. cloud