The Infinitive and Modals

1. THE INFINITIVE AND MODAL VERBS

Indefinite
Infinitive
To learn
I must learn to dive.
Continuous
Infinitive
To be learning
Why have you bought goggles? You must be
learning to dive.
Passive
Infinitive
To be learnt
Diving must be learnt! (Instructor)
Perfect
Infinitive
To have learnt
Wow! You must have learnt to dive!
Perfect
Continuous
Infinitive
To have been
learning
You must have been learning to dive all your
life!
?