Maybe if I science，and not literature then，I would be able to give you more help.(2011·北京)
A. studied
B. would study
C. had studied
D. was studying
网友回答
A. studied
B. would study
(答案→)C. had studied
D. was studying
解析：考查错综时间的虚拟语气。主句用的是would be able to...表示对现在情况的假设，但由if从句中的then可知，从句表示对过去情况的虚拟，故用had studied。