21.   There is a constant flux, a turnover of letters in the message.

22.   They differ in almost half the letters in the signature site.

23.   Tom folded the letter in half and stuck it in his pocket.

24.   She came back with a letter in her hand.

25.   I found the letter in the top drawer of his desk.

26.   They saw some large letters in white paint.

27.   He had arranged the letters in stacks.

28.   C is the third letter in the alphabet.

29.   On the way to work, I dropped my letters in the corner mailbox.

30.   He balled the letter in his hands and threw it in the trash.