A:物体可能沿原曲线由B返回A
B:物体可能沿曲线Ba运动
C:物体可能沿曲线Bb运动
D:物体可能沿曲线Bc运动
选词填空。
believe,lively,rock,exercise,piece
Deng Feng is my friend.He is____and interested in music.He usually gets up at 6:00 in the morning and then he does some____in the park.He likes to listen to____music When exercising.Before going to bed,he listens to some____of light music.Sometimes he'd like to enjoy traditional Chinese music.He____it's a good way to relax.Some day,he will study music and be a musician.
①商朝②周朝③秦朝④汉朝
挖一条长1500米的引水渠,水渠横断面是一个梯形,面积是2.7平方米.
已知水渠上口宽2.4米,渠底宽1.2米,求水渠深.
已知每人每天挖土2.5立方米,计划20天完成,每天应安排多少人参加挖水渠?
如图所示,甲乙两小磁针在一根磁铁附近,下列判断正确的是( )