You're either fooled into thinking that letters like O, A, OU, EA are pronounced like they are in your native language, or if you do know English pronunciation rules, you may not be aware of all the common exceptions to the rules.
你要麼被矇蔽了,以為像 O、A、OU、EA 這樣的字母在你的母語中是這樣發音的,要麼即使你知道英語發音規則,也可能不知道規則中所有常見的例外情況。