你就放心吧，我们会千方百计找到他。

You may rest assured that we will do all we can to find him.

《牛津词典》

“你放心吧，”狼说，“我会给你出个好主意。”

"Make yourself easy," said the wolf, "I will give you some good advice."

youdao

放心吧——你的背会毫发无损的——我来想办法。

Set thy mind at ease—thy back shall go unscathed—I will see to it.

youdao

And he says, "No, no, no. We're fine." "You know, We'll get there eventually."

但你的未婚夫说，“放心吧，我们找得到的。”“我们总会到目的地的。”

I'd better 课堂 - SpeakingMax英语口语达人