回收逆向物流是指下游客户将不符合订单要求的产品退回给上游供应商。()
参考答案:错
I think _________ of the materials I listened to at the beginning of the exam __________ easy.
A.two thirds; is
B.second three; are
C.two thirds; are
D.two third; are
研究细菌的最佳时期是将细菌人工培养至()。