Learning rate is not useful when ___________ 何种情况下学习效应不起作用？

A、each item produced is significantly different from the preceding item 企业生产的每一个项目均存在巨大差异

B、rules & regulations limit the production rate 相关法律法规限制企业的产量

C、production quantities are very small 产量非常少

D、there is almost no way to improve the production rate 几乎没有从量的积累中改进提高生产率的余地

E、production is sporadic 生产过于零星