.Mr. Black has been teaching English in a middle school he came to China.
A. for ever
B. ever since
C. ever before
D. long before
网友回答
A. for ever
(答案→)B. ever since
C. ever before
D. long before
解析：考查固定词组：A. for ever曾经，B. ever since自从，C. ever before以前，D. long before很久以前，句意：自从布莱克先生到中国来一直在中学教英语。和ever since+从句，连用的主语是现在完成时，选B。