do 代替的动词,用法.Whether you believe it or not,I do..Whether you

do 代替的动词,用法
.Whether you believe it or not,I do.
.Whether you believe it or not,I believe it.
这个句子,结构我是明白了,I do 我明白 do 是 代替了动词,那这里算是 整个代替 believe it
还是说 只代替 believe?
——————————————————————————————————————
2 Whether you believe it or not,能否写成 I do it
3 No matter.句型是否后面也可以 用 or not