What do the following words have in common (other than their first letters)?

1. ID

2. IT

3. ILL

4. IRE

5. IRK  

Answer:

 

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

1. QUID (British, one pound sterling)

2. QUIT

3. QUILL

4. QUIRE (25 sheets of paper)

5. QUIRK