缩减产品组合会增加企业经营风险，但可以改进服务质量，稳定产销关系。
参考答案：对
MODIFY STRUCTURE命令的功能是
A．修改记录值
B．修改表结构
C．修改数据库结构
D．修改数据库或表结构
.
－Jim! Did you have a good time at the party?
－Yes，but with all this work on hand，I really________there．
A．needn’t have been
B．couldn’t have gone
C．shouldn’t have been
D．shouldn’t have gone
