If I ruled the world，I would________ the world________ everything that is bad.

A．get rid of；by

B．be rid of；by

C．rid；of

D．get rid；of

“商品”与“顾客”两个实体集之间的联系一般是( )。

A．一对一

B．一对多

C．多对一

D．多对多