7岁的孩子，腕部骨化中心出现的只数大约为（）
A.4个
B.5个
C.6个
D.7个
E.8个
参考答案：E
改错。
( ) 1. We are same. ______________
A B C
( ) 2. I don't like socks, too. ______________
( ) 3. We eat lunch in the morning. ______________
( ) 4. What do you like to doing? ______________
( ) 5. She like to play games. ______________
对于生命的维持和延续最重要的是[ ]
A．细胞结构和新陈代谢
B．遗传和变异
C．生长发育和新陈代谢
D．新陈代谢和生殖
