I am completely sure you can help me.
I have no doubt that you can help me.
都可以的啦.


如不明白请追问,请在客户端右上角评价点“满意”即可语境是这样的，A家中的燃气用具坏了，他和B说，我坚信你能帮我解决这个问题，希望是口语化，但又不想太中国就用I have no doubt you can handle it / figure it out。就挺好！在口语一点那就是，I trust you. 好了