正确是all of a sudden,例如:1、All of a sudden someone grabbed me around the neck.猛不防有人抓住了我的脖子。2、All of a sudden, right after the summer, Mother gets married.突然,刚过夏天,妈妈就结婚了。3、All of a sudden she didn't look sleepy any more.她突然看起来一点都不困了。