单选题：It was essential that the application forms ___ back before the deadline.
题目
单选题：It was essential that the application forms ___ back before the deadline.
选项:
a、must be sent
b、would be sent
c、be sent
d、were sent
答案
c
It was essential that +虚拟语气（should do）
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我想写一篇关于奥巴马的演讲的文章,写哪一篇好呢?为什么好
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