Random Puzzles 

Workings

Hint
What can digit 4 be?

Answer
6849.

Reasoning
Digit 4 must be a multiple of 3:
   ---3
   ---6
   ---9

Digit 3 is one more than Digit 9 ÷ 3:
   --23
   --36
   --49

Digit 2 is twice Digit 3:
   -423
   -636
   -849

But Digit 4 is one more than Digit 2, which only leaves:
   -849

And Digit 1 is three smaller than Digit 4:
   6849.

Workings

Hint
One of the words starts and ends with T.

Answers
eve    = level able   = tablet carve  = scarves as     = ease, hash, sass on     = gong, sons ode    = codec, modem elude  = deluded ape    = lapel ate    = dated, rater rod    = erode

Workings

Hint
The clue is in the question.

Answer
B.

Reasoning
These are the initial letters of the puzzle itself:
   This
   is
   a
   very
   special
   sequence
   and
   is
   complete
 * but
   what
   is
   the
   missing
   letter

Therefore, B is missing.

Workings

Hint
This is quite a common alphabet.

Answer
Z.

From Zeta, first letters of the Greek alphabet, alpha, beta, gamma, delta, epsilon, zeta, eta.