—Your shoes are so old. Why don’t you buy a new pair?—Because I all my money on an MP5.A.

问题补充：

—Your shoes are so old. Why don’t you buy a new pair?

—Because I all my money on an MP5.

A. spend

B. have spent

C. am spending

D. was spending

答案：

A. spend

(答案→)B. have spent

C. am spending

D. was spending

解析：句意：你的鞋太旧了。为什么不买一双新的？——因为把我所有的前都花在MP5上了。结合语境可知下文描述的是现在已经完成的动作，故用现在完成时态。选B。