A:15
B:30
C:31
D:64
小明拿一张50元的人民币到银行等额换取5元或10元的人民币,请问小明换钱方式有( )种.
下列有关实验室制取气体的说法错误的是( )
— Did you see the teacher come into the classroom?
一 No, I didn't I at that time.