是同义句，中文意思是，这是谁的书

Whose is that farm over yonder?那边的农场是谁的

=Whose farm is that over yonder

Whose side are you on anyway?

你到底赞成谁的观点呢

So whose party was it last night?

那么昨天晚上是谁的晚会

I can't remember whose idea it was.

我记不得这是谁的主意了。