A:光导纤维
B:电磁波
C:超声波
D:次声波
在(1+x)3+(1+x)4+…+(1+x)50的展开式中,x3的系数为( )
列宁说:“农民在获得‘自由’的时候,已经被剥夺得一干二净”。这一现象出现在( )
一长方体铁块按如图所示,从下表面与液面刚刚接触处下放至图中虚线位置.不能大致反映铁块下降过程中所受浮力的大小F浮与铁块下表面浸入液体深度h深关系的图象是( )
— Ang Lee, a Chinese director, won the Best Director again in his last year.
— How great he was! It was his time to win an Oscar.