下列哪种动物终生生活在水中？（）
A.育蛙
B.鲫鱼
C.鳄鱼
D.小狗
参考答案：B
下列保留字书写正确的是( )。
A．Byte
B．NEW
C．long
D．Null
By the time he went to the shop, all the clothes _____. [ ]
A. sold out
B. had sold out
C. had been sold out
