在一瓶无色未知溶液中检验出有Ba、Ag,同时又测得其酸性很强。某学生还要鉴定此溶液中是否大量存在:①Cu、②Fe、③ Cl、④ NO、⑤ S 、⑥ CO、⑦ NH、⑧ Mg、⑨A1、⑩离子。其实,这些离子中有一部分不再鉴定就能加以否定,你认为不必鉴定的离子组是( )
She brought with her three friends, none of ______ I had ever met before.
I tried phoning her office, but I couldn’t _______.
His sister left home in 1998, and _______since.
What do you mean, there are only ten tickets? There _____ be twelve
Could I speak to ______ is in charge of International Sales please?