商鞅变法发生在[ ]
A.商朝
B.西周
C.春秋
D.战国
答案:D
Peter_____to be a policeman when he_____up. [ ]
A. wants; grows
B. will want; grow
C. will want; grows
D. wants; will grow
四冲程柴油机每缸完成一个工作循环,曲轴旋转()。