1. Lesson 17 – future and perfect of “sum”, infinitive as subject or object preview
Before we begin please read pages “Grammar” of your textbook. This will give you a preview of what you are about to learn.
What does it mean that “the personal endings [of sum] remain regular”?
Give the future and perfect forms of sum.
Why does the perfect tense of sum have the base fu-?
How can infinitives function in a Latin sentence?

2. Lesson 17 – future and perfect of “sum”, infinitive as subject or object forms of sum
Present
1st person sum (I am) sumus (we are)
2nd person es (you are) estis (you are)
3rd person est (he/she/it is) sunt (they are)
Future
1st person ero (I will be) erimus (we will be)
2nd person eris (you will be) eritis (you will be)
3rd person erit(he/she/it will be) erunt (they will be)
Perfect and Imperfect
1st person eram/fui (I was) eramus/fuimus (we were)
2nd person eras/fuisti (you were) eratis/fuistis (you were)
3rd person erat/fuit (he/she/it was) erant/fuerunt (they were)

3. Lesson 17 – future and perfect of “sum”, infinitive as subject or object infinitives
In English, infinitives are the word “to” followed by a verb e.g. to eat
In Latin these are the second principal part of a verb e.g. spectare (to see), esse (to be)
Infinitives can sometimes function as the subject of a sentence e.g. errare est humanum (to err is human)
Infinitives can also function as an object e.g. servos liberare parat (he prepares to free the slaves)