What do the following words have in common?

1. ACRE

2. RALLY

3. ASCENT

4. MOTHER

5. SLANDER

6. ALLIANCE

7. LAUGHTER

 

Answer: 

 

Each word can be changed to a new one by placing a single letter at the beginning:

 

1. NACRE

2. ORALLY

3. NASCENT

4. SMOTHER

5. ISLANDER

6. DALLIANCE

7. SLAUGHTER