英语翻译中翻英：“他promise A,但未必会履行；即使会履行,也未必能做到A；即使能做到,也未必能……”还有“说服A

He promised A,but he might not be willing to fulfil it; even if he fulfiled the promise,maybe he couldn't make it; even if he made it,maybe he won't……
persuade A to do something
hence,such a subjective promise cannot make the argument support the conclusion.