Auxiliaries

There are four different aspects of the auxiliary verb:

1. Modal
2. Perfect Aspect
3. Progressive Aspect
4. Passive Voice

Essential points to note are:

• All four are optional
• Any combination of them is possible, but
• They always appear in the order given
• Each may only appear once

This allows for exactly sixteen combinations:

1. [no auxiliary]
2. modal
3. perfect
4. progressive
5. passive
6. modal perfect
7. modal progressive
8. modal passive
9. perfect progressive
10. perfect passive
11. progressive passive
12. modal perfect progressive
13. modal perfect passive
14. modal progressive passive
15. perfect progressive passive
16. modal perfect progressive passive

Examples:

1. He forgets.
2. He will forget.
3. He has forgotten.
4. He is forgetting.
5. He is forgotten.
6. He will have forgotten.
7. He will be forgotting.
8. He will be forgotten.
9. He has been forgetting.
10. He has been forgotten.
11. He is being forgotten.
12. He will have been forgetting.
13. He will have been forgotten.
14. He will be being forgotten.
15. He has been being forgotten.
16. He will have been being forgotten.