They've kept up a friendship with the teacher whom they were at school twenty ye
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They've kept up a friendship with the teacher whom they were at school _____ twenty years ago.
A.with
B.about
C.since
D.till
试题答案
A
易错选B或C, whom在这里指代the teacher,因此定语从句可还原为： They were at school／with the teacher twenty years ago.