—How old are you?
—I'm fifteen. I was born ______ 1990.[ ]
A. in
B. at
C. on
D. for
答案:A
公债的特征有( )。
A.安全性高
B.流动性好
C.收益稳定
D.免税待遇
世界上铜资源最丰富的国家是中国。