There is no royal road to learning.
((諺))学問に王道なし
There is no rule but has some exceptions.
例外のない規則はない
There is no rule without exceptions.
例外のない規則はない
There is no saying when this could start.
これがいつ始まるかはわからない
There is no sense in talking to him.
彼に話してもむだだ
There is no simple answer to this question.
この問題に簡単な答えはない
There is no solution in sight.
解決の糸口がつかめない
There is no substitute for experience.
経験に勝るものなし
There is no telling [saying, knowing] what may happen.
何が起こるかわからない(◆there isは省略可)
There is no virtue in what he says.
彼の言うことには何の価値もない