There was something wrong with the network， or the e-mail earlier.
A. could have been sent
B. might be sent
C. need have been sent
D. must be sent
网友回答
(答案→)A. could have been sent
B. might be sent
C. need have been sent
D. must be sent
解析：句意：网络出了问题，否则电子邮件早就到了。这里的or相当于一个虚拟条件句If There hadn’t been something wrong with the network，由此可知是和过去相反的虚拟语气，主句应该用could/should/would have done，所以选A。