根据我国《合同法》,由于债权人的原因致使债务人难以履行债务时,债务人可以将标的物交给有关机关保存,以此消灭合同的行为称为( )。
A.留置
B.保全
C.质押
D.提存
参考答案:D
It's _____ problem _____ we can't work it out.[ ]
A. so confused a; that
B. such a confusing; that
C. such confusing a; so that
D. so a confused; so that
用基准氧化锌标定EDTA滴定液时,ZnO与EDTA的摩尔比
A.1∶1B.l∶2C.1∶4D.l∶3E.1∶6