理财卡卡内同一种类的子账户只能开立()个。
A.2
B.3
C.1
D.4
参考答案:C
Scientists are convinced _____ the positive effect of laughter _____ physical and mental health.[ ]
A. of; at
B. by; in
C. of; on
D. on; at
包装的形式分()。
A.卷状包装
B.板状包装
C.表面精度
D.单组分胶粘剂
E.卧式包装