问题描述：
27.i saw ann inthe library yesterday.You ____ her,she is still abroad.
A)could not see
B)cann’t have seen
C)must not haveseen
D)had not seen
请问为什么选择B呢,
A)could not see
B)cann’t have seen
C)must not haveseen
D)had not seen
请问为什么选择B呢,
问题解答：
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