He has been collecting coins he was seven years old.A. becauseB. whileC. whenD. since

问题补充：

He has been collecting coins he was seven years old.

A. because

B. while

C. when

D. since

答案：

A. because

B. while

C. when

(答案→)D. since

解析：考查连词。句意：自从他七岁的时候他就一直收集硬币。Since自从，故选D。