单选题The boy finally was 

问题补充：

单选题Theboyfinallywasbeginning___hismistakes.A.that he sawB.for him to seeC.seeingD.to see

答案：

D解析start, begin 等词的进行时,不用动名词做宾语,所以不选C. A B两项的语法结构不对.