He said he had left Beijing when he was ten.
直接引语在改为间接引语时、时态需要做相应的调整.
现在时它需改为过去时态；过去时态改为完成时；过去完成时则保留原来的时态.如：
1)She said. "I have lost a pen."→She said she had lost a pen
2)She said. "We hope so."→She said they hoped so.
3) She said. "He will go to see his friend."→She said he would go to see his friend.
但要注意在以下几种情况下.在直接引语变为间接引语时,时态一般不变化.
①直接引语是客观真理.
"The earth moves around the sun and the moon moves around the earth, the teacher told me. → The teacher told me the earth moves around the sun and the moon moves around the earth.
②直接引语是过去进行时,时态不变.如：
Jack said. "John, where were you going when I met you in the street?"→Jack asked John where he was going when he met him in the street.
③直接引语中有具体的过去某年、某月、某日作状语,变为间接引语时,时态不变.如：
Xiao Wang said. "I was born on April 2l, 1980." →Xiao Wang said he was born on April 20, 1980.
④直接引语如果是一般现在时.表示一种反复出现或习惯性的动作,变间接引语,时态不变.如：
He said, "I get up at six every morning." →He said he gets up at six every morning.
⑤如果直接引语中的情态动词没有过去时的形式（例：ought to, had better, used to)和已经是过去时的形式时,（例：could, should, would, might）不再变.如：
Peter said. "You had better come have today." →Peter said I had better go there that day.