Duo libri in mensa sunt, et discipula eum legit qui brevior est.

Because libri is masculine plural nominative, and duo is the masculine nominative form of two.

The numeral two changes for gender in Latin:

• duo = masculine
• duae = feminine
• duo = neuter

So:

• duo libri = two books
• duae puellae = two girls
• duo templa = two temples

Here, libri is masculine, so duo is the correct form.

Libri is the nominative plural of liber (book).

It is nominative plural because it is the subject of sunt:

• Duo libri ... sunt = Two books ... are

Latin marks the role of a noun by its ending, so libri tells you that the books are the thing being talked about as the subject.

Because in can take either the ablative or the accusative, depending on the meaning.

• in + ablative = in/on a place, showing location
• in + accusative = into / onto a place, showing motion toward

Here the books are already there, so this is location:

• in mensa = on the table or in the table area, depending on context

So:

• libri in mensa sunt = the books are on the table
• but libros in mensam pono = I put the books onto the table

Because after in meaning in/on for location, Latin uses the ablative case.

The noun mensa belongs to the first declension:

• nominative: mensa
• ablative: mensā

In normal classroom writing, the long vowel mark may or may not be shown. So mensa in the sentence is understood as ablative by context, even if the macron is omitted.

Because its subject, duo libri, is plural.

Latin verbs agree with their subject in number:

• liber est = the book is
• libri sunt = the books are

Since there are two books, the verb must be sunt.

Yes. Discipula means female student or schoolgirl. It is the feminine form.

Compare:

• discipulus = male student
• discipula = female student

So the sentence specifically tells you the student is female.

Grammatically, discipula is nominative singular, because she is the subject of legit.

Because eum means him/it in the masculine singular accusative, and here it refers to one book, not both books.

The idea is:

• There are two books on the table.
• The student reads the one that is shorter.

Latin does not need to repeat librum here. Instead, it uses eum = that one / it.

Since liber is masculine, the pronoun is masculine too:

• eum = masculine singular accusative

And it is accusative because it is the direct object of legit.

Because eum is the direct object of legit (reads).

The student is doing the action of reading, and eum is the thing being read. In Latin, direct objects usually go in the accusative case.

So:

• discipula legit = the student reads
• discipula eum legit = the student reads it / that one

This is a very common question.

Even though qui refers back to eum, its case depends on its role inside the relative clause, not on the case of its antecedent.

Here is the structure:

• main clause: discipula eum legit
• relative clause: qui brevior est

Inside the relative clause, qui is the subject of est, so it must be nominative.

That is why Latin has:

• eum = accusative, because it is the object of legit
• qui = nominative, because it is the subject of est

A useful rule: A relative pronoun agrees with its antecedent in gender and number, but its case comes from its job in its own clause.

Because relative pronouns in Latin do not have to match their antecedent in case.

They match in:

• gender
• number

But the case is determined by the pronoun's own function in the relative clause.

So here:

• antecedent: eum = masculine singular accusative
• relative pronoun: qui = masculine singular nominative

They still match in masculine singular, so the connection is clear.

Brevior is the comparative form of brevis, meaning shorter.

So:

• brevis = short
• brevior = shorter

Since it describes the book referred to by qui, it is masculine nominative singular here to agree with qui.

The phrase qui brevior est means:

• which is shorter
• or more naturally in English, the one that is shorter

It is understood from the context: there are two books, and the student reads the shorter one.

Latin often leaves the second item in a comparison unspoken when it is obvious. English does this too:

• Take the smaller one.
• I chose the faster horse.

You do not have to say smaller than the other one every time, because the comparison is already clear from the context.

Because Latin often avoids repeating a noun when a pronoun is enough.

Instead of saying something like:

• discipula librum legit, qui brevior est

this sentence uses:

• discipula eum legit, qui brevior est

The pronoun eum efficiently means that one / it, and the relative clause identifies which one is meant.

English often does something similar with the one.

It is flexible rather than unusual.

Latin word order is much freer than English word order because the endings show grammatical roles. So Latin can place words in different positions for emphasis or style.

This sentence is quite natural:

• Duo libri in mensa sunt
• et discipula eum legit qui brevior est

A more literal word-by-word order in English might feel awkward, but in Latin the endings make the relationships clear.

For example:

• duo libri = subject
• in mensa = location
• discipula = subject of the second clause
• eum = object
• qui brevior est = relative clause describing eum

No, not here.

Qui is masculine singular, so it must refer to a masculine singular antecedent. Discipula is feminine, so it cannot be the antecedent.

The masculine singular antecedent is eum, referring to one book.

If the relative pronoun referred to discipula, you would expect a feminine form such as quae.

Legit is third person singular present in this sentence:

• discipula legit = the student reads

In some contexts, legit could also be confused with a perfect form in isolation, but with the verb lego the present is normally understood here from the context and standard textbook usage.

So in this sentence it means reads.

The pattern is:

• discipula = subject
• eum = direct object
• legit = verb
• qui brevior est = relative clause describing eum

So the second half works like:

The student reads it, namely the one that is shorter.

More naturally in English: the student reads the shorter one.