cannothave的意思?Duringthattime,theirparentscannothaveclaimedthemasadependentonthefamily'staxforms.这句话为什么用cannothave,而不是can't?有什么作用吗?

Question

cannot have的意思?
During that time,their parents cannot have claimed them as a dependent on the family's tax forms.
这句话为什么用 cannot have,而不是can't?有什么作用吗?

Answer 1

这句话可以看作是过去将来完成时,从过去某时来看将来某时已经完成的动作.如：She said she’d have finished her exams by then.她说那时她会已经考完试了.The party would have arrived by four o’clock.这一行人...