What do the following words have in common?

1. TREE

2. DIVE

3. CORE

4. TIRE

5. GLAND

 

HINT:

The same two letters, properly positioned, will change each word into a new one.

 

Answer:

 

Each word can be preceded by EN to make a new word:

 

1. TREE - ENTREE

2. DIVE - ENDIVE

3. CORE - ENCORE

4. TIRE - ENTIRE

5. GLAND - ENGLAND