in order that 和 so that 用法,
he posted the letter early in the morning _________it in the afternoon.
A.in order that she recerved B.so that she could receive
C.so that it can be received D.in order that it could receive
选择哪一个?答案说选择B啊.
帮我解释这四个选项的区别,如何排除的,为什么我看哪个都对呢?