We warned them, but to no effect.

我们曾告诫过他们，但没起任何作用。

He spoke to no effect.

他讲话不起作用。

We tried to persuade him to no effect.

我们设法说服他，却一点儿用也没有。

She frowned and frowned, but to no effect.

她把眉头皱了又皱。但是什么效果也没有。

We tried again and again, but to no effect.

我们试了又试，但毫无效果。