Magistra rogat cur discipuli hodie sero veniant et utrum mora in vico fuerit.

Because cur discipuli hodie sero veniant and utrum mora in vico fuerit are both indirect questions depending on rogat.

In Latin, indirect questions normally take the subjunctive. So after a verb like rogat (asks), Latin uses:

• cur ... veniant = why ... they are coming / come
• utrum ... fuerit = whether ... there was / has been

English does not usually show this difference clearly, but Latin does.

They show different time relationships to rogat.

• veniant is present subjunctive because the coming late is viewed as happening at the same time as the asking, or as a current matter.
• fuerit is perfect subjunctive because the delay is viewed as already completed before the asking.

Since rogat is a present-tense main verb, this follows normal primary sequence:

• same time: present subjunctive
• earlier time: perfect subjunctive

Utrum means whether and introduces a yes/no indirect question.

So utrum mora in vico fuerit means whether there was a delay in the street/neighborhood/village.

It is a common way in Latin to mark an indirect question whose answer could be yes or no.

Discipuli is nominative plural, and it is the subject of veniant.

We know this because the students are the ones doing the action of coming late. The ending -i can sometimes be ambiguous in Latin, but here the syntax makes the function clear: discipuli must be the students as the subject.

Sero is an adverb meaning late.

It modifies veniant, telling us how they are coming:

• hodie = today
• sero = late

So hodie sero veniant means they come / are coming late today.

Mora means delay and is nominative singular because it is the subject of fuerit.

Latin often expresses this idea with esse:

• mora fuit / fuerit = there was a delay

So literally, utrum mora in vico fuerit is something like whether a delay has been in the street, but natural English is whether there was a delay in the street.

In vico is a prepositional phrase.

• in
  • ablative often means in or at a place
• vico is ablative singular of vicus

So in vico means in the street, in the neighborhood, or in the village, depending on context.

A useful point to remember is that in with the ablative usually shows location, while in with the accusative often shows motion into a place.

The main clause is:

Magistra rogat = The teacher asks

Then come two indirect questions, joined by et:

• cur discipuli hodie sero veniant
• utrum mora in vico fuerit

So the structure is:

The teacher asks

1. why the students are coming late today
2. and whether there was a delay in the street/neighborhood/village

Because this is an indirect question, not an indirect statement.

Latin usually uses:

• accusative + infinitive for indirect statement
• subjunctive for indirect question

Since cur and utrum introduce questions, Latin naturally uses veniant and fuerit, not infinitives.

So this sentence is a good example of the difference between:

• reporting what someone says
• reporting what someone asks