问题补充：
Tommy was planning to buy a car the next week, he enough for a used one．
A. by that time; had saved
B. by which time; had saved
C. by that time; saved
D. by which time; has saved
答案：
A. by that time; had saved
(答案→)B. by which time; had saved
C. by that time; saved
D. by which time; has saved
解析：考查从句和时态，从句he …enough for a used one缺少成份，所以选which，by…的时间状语，时态是完成时，有前面的句子是过去式，所以用过去完成时，所以是had saved，句子意思“汤米打算下周买一辆车，到那个时候他已经节省足够的钱买个二手车”，所以选B
