题型:填空题 -There is a mobile phone on the desk. Is it Li Yong's?-It __________ Li Yong's. He went to Shanghai two days ago.[ ]A. can beB. can't beC. must beD. might be 查看答案
题型:填空题 某承包商从一生产厂家购买了相同规格的大批预制构件,进场后码放整齐。对其进行进场检验时,为了使样本更有代表性宜采用()的方法。A.全数检验 B.分层抽样 C.简单随机抽样 D.等距抽样 查看答案