选择表面涂层时需要注意的是（）。
A、有较强抗腐蚀性能
B、有很好的填充性能
C、有防锈材料和抑制性颜料
D、容易打磨
参考答案：A
—Why didn't you give the wallet to the man at once?
—He _____ before I realized it was his . [ ]
A. had been disappeared
B. has disappeared
C. had disappeared
D. has been disappeared
影响家畜营养代谢病发生的最主要因素是（）。
A.年龄
B.遗传
C.品种
D.性别
E.生产与管理
