1. The same three letters, but not in the same order, will complete the words below:

P _ _ _
CA _ _ _ 
P _ L L  _ _
H _ I _ _ US

2. Can you think of a word that can either follow or precede /all of the following words:

on/off/in/out/over/under/long/short

3. Can you think of a word that means both assemble and physique?

HINT:
1. ST _ _ _  (and many others) could be added to the list.

Answers:

1. The letters are O, N, and E.

PEON/CANOE/POLLEN/HEINOUS

(HINT: STONE/PHONE/BONE/DONE, etc.) 

2. HAND 
3. BUILD