He is afraid to speak English. 這裡的to是「不定詞的記號」，to speak是「不定詞」 ...something very unpleasant is going to happen to you. 所以這裡的片語是to be afraid to do something=害怕做某種事 to也以是一個「介系詞」，用在名詞之前，形成介系詞...
ain't afraid to die 就是i am not afraid to die ain't 是i am not的連音，就是把這三個字連在一起發音 但這是較為口語的用法 就是這樣..
afraid of +N. afraid to +V. afraid that+S.+V. 應該是I am afraid that you lie to me.