下图提示心脏的病理改变为（）
A．右房扩大
B．左房扩大
C．左心室肥大
D．右心室肥大
E．双侧心室肥大
参考答案：B
青少年如果不注意坐、立、行走的正确姿势，会造成驼背、脊柱侧弯的原因是 [ ]
A．骨质疏松
B．骨内无机物含量较多
C．骨密质薄
D．骨内有机物含量超过1／3
After playing football for more than half an hour, the students took ______rest. [ ]
A. a few minute's
B. a few minutes'
C. a little minute's
D. a little minutes'
