I don't think you should do that until___another job

I don't think you should do that until___another job
I don't think you should do that until_B__another job.
A.you'd found
B.you've found
C.you'll found
D.you'd find
I won't tell the student the answer until he_A__on it for more than an hour.
A.has been working
B.will have worked
C.will have been working
D.had worked
为什么选哪两个,还有说明一下until,not until 的题,前后时态怎么想
不好意思，第一题C就是you'll find
midnight13说得已经比较明白了，
是说主从句要现在时都现在时，要过去时都过去是么
还有“will后面不能加过去时态的”应该不对。will have worked是将来完成时，will have been working是将来完成进行时