He ____ down his life for the cause of freedom.
A.gave
B.took
C.killed
D.laid
答案:D
一个物体在水平面上从静止开始做匀加速直线运动,加速度大小为a。从开始运动经过时间t,物体运动的距离为()
A.at
B.½at
C.at2
D.½at2
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