has he sent the letter?does he send the letter?did he send the letter?三句有何不同如何翻译

has he sent the letter?does he send the letter?did he send the letter?三句有何不同如何翻译
has he sent the letter?does he send the letter?did he send the letter?三句有何不同如何翻译

has he sent the letter?does he send the letter?did he send the letter?三句有何不同如何翻译
他信已经发出?难道他送一封信?他才寄出的信?