信的單詞怎麼寫

letter:a written or printed message that is usually put in an envelope and sent by mail 信，信件

letter是作“信，信件”是可數名詞，通常與動詞post,mail,read,receive,send,,write搭配，也就是說

寫信write a letter

寄信post/mail/send a letter

收到信receive/get a letter

閱讀信read a letter