Recently, I have experienced constant problems in the computer rooms, so I think it is about time we __________ new computers.
A:have
B:have had
C:had
D:will have
已知1a+1b=1a+b,则ba+ab的值为( )
校园周边所售某食品自开学以来,每包价格从4元涨到了5元,其销量却不降反升。对这种现象的合理解释应该是( )
①该食品质量上乘、适销对路
②生产该食品的劳动生产率提高
③学生手中的零花钱越来越多
④该食品的替代品价格增幅更大