l certainly can't disagree with you不低吧 好像是赞同吧。不然听力答案就不对了？

l certainly can't disagree with you不低吧 好像是赞同吧。不然听力答案就不对了？
l certainly can't disagree with you
不低吧 好像是赞同吧。不然听力答案就不对了？

l certainly can't disagree with you不低吧 好像是赞同吧。不然听力答案就不对了？
我当然不能不赞同你（我当然赞同你）

我当然不能赞同你...
我错了= =

双重否定表肯定
我当然赞同你

双重否定等于肯定：我当然不能不赞同你。