1. What do the following words have in common?

SICK
SEAT
LIFE
LETTER
HANDLE

2. What do the following words have in common?

BEND
SAGE
FLEX
EDIT
WENT

HINTS:
1. AFFAIR and POTION could be added to the list.
2. The same change to the same letter in each word will create new words.

Answers:

1. Each word can be preceded by LOVE. 

2. The "E" in each word can be changed to "A" to give new words:

BAND /SAGA / FLAX / ADIT / WANT