下列变化中，属于物理变化的是 [ ]
A．浓盐酸挥发
B．氢氧化钠变质
C．铁生锈
D．二氧化碳灭火
答案：A
鸟的飞行器官是羽毛．______．
________ I was born in America,my English is not good.[ ]
A. If
B. When
C. Because
D. Although
