this ( ) ( book) these(?)( book) this(this ( ) ( book)these(?)( book)this( ) (key)these(?)(key)that(?) (box)those(?)(box)

问题描述:

this ( ) ( book) these(?)( book) this(
this ( ) ( book)
these(?)( book)
this( ) (key)
these(?)(key)
that(?) (box)
those(?)(box)

is
are
is
are
is
are