Please tell him about it when you see him back.

你看到他回来，就告诉他这件事。

youdao

Please tell him about it as soon as he comes back.

他一回来，就请把这件事告诉他。

youdao

Please tell him about it as soon as he comes back.

他一回来，就请把这件事告诉他。

youdao