在批次需求计划子系统中，对批次生产计划进行维护时应使用（）模块避免系统对该生产计划进行其它操作。
参考答案：锁定生产计划
I've become good friends with several of the students in my school ________ I met in the English
speech contest last year.[ ]
A. who
B. where
C. when
D. which
带和带轮应保持干净，不得沾有油和水。
