因为后面的时态不对
如果你填since,应该是It was ten years since he had returned to his hometown.
有一个结构是It is +一段时间+since +一般过去时
is-was,一般过去时-过去完成时, (变成相应的过去时态)
所以用before
因为后面的时态不对
如果你填since,应该是It was ten years since he had returned to his hometown.
有一个结构是It is +一段时间+since +一般过去时
is-was,一般过去时-过去完成时, (变成相应的过去时态)
所以用before