lily could not have accepted the invitation-----?

高一英语题Mary could not have accepted the invitation,____? A.has _____singer and ____dancer has accepted the invitation Since you've accepted the invitation ,I'll__accept it.A.too When he got the invitation,he accepted it with ___________ p could not have done The United States could not have lasted long against the ... __we could not have finished the work on time. must not have been;could not have Any applicant from ____properly will not be accepted by the Any application form --properly will not be accepted by the Any applicant form___properly will not be accepted by the co could not have done是什么意思?