He doesn’t have the habit of planning his travel expense, so he won’t know what to do the

He doesn’t have the habit of planning his travel expense, so he won’t know what to do the money runs out.
A. once
B. before
C. unless
D. though

(答案→)A. onceB. beforeC. unlessD. though解析：连词辨析。A.一旦 B.在……之前 C. 除非 D. 尽管。句意：他没有计算旅行费用的习惯，因此他不知道一旦钱用完了该怎么办。故选A。

这个问题的回答的对