47. By the time the software __________ on sale next month, the company __________ $2 million.
A. went - has spent
B. will go - has spent
C. goes - will have spend
D. has gone - will spend

48. When Carol __________
A. called / was watching
B. was called / have watched
C. called / have watched
D. was calling / had hiked

49. Linda took great photos of butterflies while she __________ in the forest.
A. was hiking
B. is hiking
C. had waited
D. had hiked

50. When I  __________ for my sister
A. was waiting
B. were waiting
C. had waited
D. had hiked