Perhaps, but not certainly so.

这不无可能，但也不是毫无疑问。

youdao

With great efforts one may not certainly succeed, but he will never regret trying hard.

努力虽然不一定成功，但努力过便不会后悔。

youdao

With great efforts one may not certainly succeed, but he will never regret trying hard.

努力虽然不一定成功，但努力过便不会后悔。

youdao