You can rest assured that I will do my best.

但你放心，你不会看到我了。

youdao

You rest assured that I will do all I can to help you.

你放心我会尽我一切力量去帮你。

youdao

You rest assured that I will do all I can to help you.

你放心我会尽我一切力量去帮你。

youdao