Based on the context and the answer, generate a question. 

Context: The Doctor looked back when they made it , and saw that the ski lodge was gone . That was n't all , however : the mountain was now disappearing at about the same rate . " Where 's Jack ? " asked Martha , worry in her eyes . " He 'll be here , " said the Doctor .

Answer:

He is someone that Martha deeply cares about .



What may be a plasuible fact about Jack ?