合金具有许多优良的性能．下列物质属于合金的是（ ）
A．钠
B．硫
C．青铜
D．氧化铜
答案：C
填空。
1. I ___________ with my feet.
2. I write with my ___________.
3. I hear with my ___________.
4. I eat with my ___________.
5. I see with my ___________.
子宫内膜有何特点？
