同学你好，该知识点来自沪江网校《美国生活文化ABC【随到随学班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学好～

presumably 大概；很可能；也许；据推测 If you say that something is presumably the case, you mean that you think it is very likely to be the case, although you are not certain.
例如：The spear is presumably the murder weapon. 这支鱼叉可能就是凶器。

probably 大概；或许；可能 If you say that something is probably the case, you think that it is likely to be the case, although you are not sure.
（用于缓和语气）大概，或许，可能 You can use probably when you want to make your opinion sound less forceful or definite, so that you do not offend people.
例如：He probably thinks you're both crazy!他可能认为你们两个人都疯了

通过英英解释，基本可以理解为presumably比probably可能的程度更大一些且用法更正式一点～

祝同学学习愉快～