STUMPERS DI

The words HIS and ALONE can be changed into two other words by the addition of the same two consecutive letters to each word. The two letters may be added anywhere in the words. What are the letters and what are the new words?

HINTS:

1. The two letters are added inside HIS and at the front of ALONE. 

2. The two letters are alphabetically consecutive.

Answer:

By adding the letters AB to each word, you get HABITS and ABALONE.