I don't know / have no idea / am not sure to what degree you know / understand each other.
I don't know / have no idea / am not sure to what degree there is understanding between you both / you two.
i don't know how deep you understand each other
deep 是形容词，要用deeply~
内容全部来源于网络收集，如有侵权，请联系网站删除：QQ：24596024