One of the problems with English is that there are no consistent rules for spelling or pronunciation. You can't look at a word and be certain. You pretty much have to rely on memorization.
I used to teach English to Spanish-speakers at the local community college, and it was tough for the the students (and me) to understand why, in English, words with different spellings were pronounced exactly the same. Examples are to-too-two, ate-eight, I-eye-aye, write-right-rite,would-wood, their-there-they're, bear-bare, and son-sun.