1. Complementary Infinitives
Chapter 5

2. What is an infintive? In English, an infinitive is “to”+ a verb.
Examples: to walk
to play
to live
to learn
to love

3. Latin Infinitives
In Latin, an infinitive is the Second Principal Part of the verb that you find in the dictionary entry.
All regular infinitives end in the letters –re.
Examples: amāre
monēre
capere
munīre

4. Complementary Infinitives
Some verbs need an infinitive to finish the thought. These are called “complementary” infinitives, because they “complete” the verb.
Examples: …want to play
…ought to run
…are able to read

5. Possum and the Complementary Infinitive
Possum is one of those verbs that is often followed by a complementary infinitive.
“I am able” doesn’t make a lot of sense on its own. It needs an infinitive to complete the thought.
Example: I am able to climb a tree.

6. In Latin…
In Latin, the infinitive is simply the second principal part of a verb. You do NOT conjugate an infinitive.
We were not able to hear. Audīre non poteramus.