2018年解放军文职招聘考试——英语93

 {00}Many _______ has been sent out to scientists from different fields. 

A.a invitation
B.an invitation
C.invitations
D.an invitations
解析：
本题选B。

{00}It ________ Joan and Mary that left school yesterday.
A.is
B.are
C.were
D.was
解析：
本题选D。