I have a book then
I is the subject, the one that has, and
a book is the direct object, the thing that is had. Only active verbs can have direct objects (these are called transitive verbs) but not all active verbs take direct objects (these are called intransitive verbs). Some verbs can be either, depending on context.
Examples of transitive verbs:
He eats an apple. (
He is the subject, doing the eating;
an apple is the direct object, being eaten)
They finished their homework. (
They is the subject, doing the finishing;
their homework is the direct object, being finished)
Examples of intransitive verbs:
We swim. (
We is the subject, doing the swimming)
You will fall. (
You is the subject, doing the falling)
Not all verbs are active.
to be is what's called a copula, a stative verb, or a linking verb. This kind of verb takes a subject complement. That is, whatever comes after the verb serves to describe the subject.
Examples of stative verbs:
She looks tired. (
tired describes the subject
The cake smells delicious. (
delicious describes the subject
When do you know to put -o and when to put -on? I'm totally confused, please try to explain as simply as possible.
The -n suffix marks the accusative case, which most of the time is the direct object of a transitive verb. It is the thing that receives the action.
Mi amas lin. I love him. Whom do I love? Who is loved?
Li amas min. He loves me. Whom does he love? Who is loved?
Verbs like "esti" aren't even transitive/intransitive, as that only applies to active verbs. Verbs like "esti" are stative verbs. They serve to compare or equate the subject with the predicate. What comes after the verb receives no action, but rather relates back to the subject.
La libro estas granda. The book is big. How would you describe the book?
In Esperanto, you can also turn adjectives into verbs. "La libro grandas" is equivalent to "La libro estas granda".
The subject is in the nominative case.
The -n suffix is only for the accusative case. If a noun phrase is the direct object of a verb, then you would put it in the accusative.
Mi legas libron = I read a book.
Here, "libron" is the direct object of "legas". It is the thing being read.
"Mi" is the subject, so it is "mi" and not "min".
Mi amas vin = I love you.
Vin amas mi = I love you.
Vi amas min = You love me.
Min amas vi = You love me.