把一小块钠投入到硫酸铜溶液中，生成物有 [ ]
A.Cu
B.Cu（OH）2
C.H2
D.O2
BC
在Windows操作系统的回收站中，只能恢复______。
A．从软盘中删除的文件或文件夹
B．从硬盘中删除的文件或文件夹
C．剪切掉的文档
D．从光盘中删除的文件或文件夹
— It has been dry for a few months.
— You’re right. There is twice ____ rain this year than _____ of last year.
A．more; it
B．less; that
C．more; that
D．less; it
