— How long have you been collecting shells?— .A. After I left schoolB. Before I moved here

问题补充：

— How long have you been collecting shells?

— .

A. After I left school

B. Before I moved here

C. When I went to the beach

D. Since I was ten years old

答案：

A. After I left school

B. Before I moved here

C. When I went to the beach

(答案→)D. Since I was ten years old

解析：回答How long的提问用since。你收集贝壳多长时间了？自从我十岁时。