1 it makes no sense to do sth == it is not a sensible thing to do sth
------- it makes no sense to explain it to her.She already knows it .
2 可以说,英语中没有 it makes no sense doing sth 这个表达.只有 there's no sense (in) doing sth这个表达== it is not sensible ：
-------There's no sense (in) worrying about it now .it's done already.