如图所示,某质点沿半径为r的半圆弧由b点运动到a点,则它通过的路程和位移分别是()
A.2r;2r,向东
B.πr;2r,向西
C.2r,向西;πr
D.2r,向东;2r
参考答案:B
In order to by the education circle, he woks very hard.
A.make himself recognized
B.make him recognize
C.get him to recognize
D.get him recognized
新生儿正常的呼吸频率为()
A.25~30次/分
B.30~35次/分
C.35~40次/分
D.40~45次/分
E.45~50次/分