1. The same three-letter word will complete the partial words below:

_ _ _ LESS

_ _ _ URE

_ _ _ ORSE

_ _ _ ING

_ _ _ IVE

_ _ _ EAR

2. The same three-letter word will complete the partial words below:

SW _ _ _
_ _ _ Y
_ _ _ OR
T _ _ _ AC
AL _ _ _
E _ _ _ ARK 

Answers:

1. The word is END.
2. The word is ARM