whose pens are these?this one is mine ,the other （must） be Mary's,这里为什么用must?而不是用can,could

whose pens are these?还是whose are these pen?区别? Whose pens are these?(Betty)They____________. 请问一下whose pens are these回答除了they are her pens是否还能回答成these pens are her或these are her pens? Are these pens ___? Whose pens are these?(their) are (we).用括号中所给形式填空 whose pens are these?____(these/they) are minewhose pens are these?____(these/they) are mine these和they 两者皆可吗?抑或只能用they?若只能用they为什么? These pens are your.henna Whose keys are these? whose sunglass are these? These are my pens同义句 These pens _______ 连词成句：are pens whose they These are our pens .They are（）. These pens are().()are over there. 用代词的适当形式填空whose pens are these?they are ___(we)our eyes are black .___(us)come from japanthese book are__(we) Are these pens?是一般疑问句吗? These pens are blue 改为一般疑问句 Are these your pens 同意句 are these your pens?做肯定回答