I am about to turn 18 and I’m planning to try and visit every continent (apart from Antarctica) before I’m 21, so I have Asia, Australasia, South America and Africa left... What’s the most useful language for me to learn to help me get by? I already know a little French, enough to ask for directions etc but I wanted to know what else I should learn particularly for Asia?

我快年满18岁了,我打算在21岁之前去各个大洲(除了南极洲)旅游,所以我的目的地是亚洲、澳大利亚、南美和非洲,为了应付旅行上的困难,我应该学的最有用的语言是什么?我会一点法语,足以用来问路之类的了,但我想知道我还应该学些什么,特别是亚洲的?