A: the; the
B: the; /
C: /; the
D: . /; /
根据图画提示完成对话
Mike is a very cool boy. He very likes Chinese food. He likes ____, but he can't use ____. Mike's friend Wu Yifan lies ____. He can use ____ and ____now. Their teachers Miss White is beautiful . She likes ____and ____. She can use ____.
如图为元素周期表中钠元素的相关信息,下列说法正确的是( )
微风吊扇通电后扇叶转动,使微风吊扇转动的工作原理是____.拔下插头,在插头处接发光二极管,用手旋转叶片,发光二极管发光,这是____现象,人们利用这一原理制成了____.
一辆汽车向山崖开去,在离山崖710m时司机按了一下喇叭,经过了4秒钟他听到了回声,声音在空气中的传播速度为340m/s,求:
(1)汽车的速度是多少?
(2)当司机听到回声时离山崖多远?