Words formed from any letters in past, plus optional blank

The value of the blank, or of an existing letter already on the game board, is shown at the start of each line.

5 letters

c - pacts  

n - pants  

4 letters

f - fast   fats  

q - qats  

z - spaz   zaps  

3 letters

f - fas   aft   fat  

j - taj  

q - qat  

v - vas   tav   vat  

x - pax   sax   tax  

z - zap