I suspect that, of all European languages, English is the one where the pronunciation of a word gives the least certainty about the spelling; and, of course, the opposite also applies: the pronunciation cannot always be assumed from the spelling. Consider the following rhyme, or rather non-rhyme, guaranteed to perplex anyone who isn't a native speaker of the language; and, for that matter, many who are:-
There once was a baker of Slough
Who brought all his bread to the Borough
But alas for the dough!
Through being too tough
It gave all the people bad coughs.
I remember as a boy reading how a snake "sloughed its skin", and making the unwarranted assumption that the word was pronounced as in the town of Slough. And indeed, how was I supposed to know any better?