这样做是为了避免读音上的变化，因为 c 和 g 一般在 e 和 i 之前弱读，在 a 或 o 之前则重读。
B 以 ce 结尾的词，加后缀 ous 时要将 e 变为 i：
grace，gracious
space，spacious
malice，malicious
vice，vicious
You can memorize words in an efficient way if you pronounce them reasonably. Say words correctly, and you will learn them easily. Correct pronunciation means correct spelling of the words. English spelling is not good to guide its pronunciation. But spelling and pronunciation have closed relationship. They match each other perfectly. Sometimes we can pronounce a word according to its spelling. English pronunciation can also guide its spelling. This is a two-way communication.
