my aunt got her bachelor's degree at 19 and her master's degree at 21
问题描述：
my aunt got her bachelor's degree at 19 and her master's degree at 21
--oh,she____a smart student
a.must be b.has always been c must have been d has to besuffering
答案是选c的,请问为什么呀 最好每选项都讲一下~
不好意思 D 是 had to be 看错了。
答
A.一定是 指现在
B.一直是 包括现在
C.这个是表示对过去的肯定推测 以前一定是
D.不得不