1. What do the following words have in common?

TALE
PIER
FLIER
CHEER

2. What do the following words have in common?

PAST
SENT
VEST
COUNT
INFANT

3. What do the following words have in common?

WHITE
BLUE
GREEN

HINTS:
1. The same two letters can be inserted into each word.
2. The same three letters can be added to each word.
3. The same word can follow each clue word.

Answers:

1)
TACKLE
PICKER
FLICKER
CHECKER

2)
PASTRY
SENTRY
VESTRY
COUNTRY
INFANTRY

3. Each word can be followed by COLLAR. White collar for professional jobs, blue for the trades, and green for environmental (or environmentally friendly).

Credits
#1: LA Times Crossword
December 4, 2009
Jack McInturff

2: LA Times Crossword
December 18, 2009
Dan Naddor