BUILDING BLOCKS II
Credit: GAMES Magazine - June, 1984
Will Shortz

The last three letters in each line of this puzzle are already in place. To solve, insert the "blocks" below onto the remaining blanks - without re-arranging any letters - to complete eight nine-letter words reading across. Each of the blocks will be used exactly once. When all the blanks have been filled in, two of the columns reading down will spell a pair of additional, related words.

CON   CRI    ETI    FAL   HOR   IST   MAG   NES
PEN   QUE   REG   SEB   SEH   STR   TER    THO


_ _ _ _ _ _  ACK
_ _ _ _ _ _  ION
_ _ _ _ _ _  USE
_ _ _ _ _ _  RAR
_ _ _ _ _ _  OOD
_ _ _ _ _ _  TTE
_ _ _ _ _ _  AIN
_ _ _ _ _ _  IUM

Answers:

HORSEBACK
CRITERION
PENTHOUSE
REGISTRAR
FALSEHOOD
ETIQUETTE
CONSTRAIN
MAGNESIUM