you'll be able to succeed mainly depends on you do and you do it.
A. If; what; why
B. Whether; how; why
C. That; whether; how
D. Whether; what; how
网友回答
A. If; what; why
B. Whether; how; why
C. That; whether; how
(答案→)D. Whether; what; how
解析：考查名词性从句。分析句子结构可知,第二空应该是做do的宾语,引导on后面的宾语从句,只能用what,第三空应该是do it的方式状语,用how,那么第一空则应该是个主语从句,一般疑问句改成主语从句只能用whether引导,不能用if。