Cum responsum dubium est, magistra rogat ut discipula sinceram sententiam aperte dicat.

Because cum can be two different things in Latin:

• as a preposition
  • ablative, it means with
• as a conjunction, it means when, since, or although

In Cum responsum dubium est, cum introduces a clause, so it is a conjunction: when/since the answer is uncertain.

Not every cum clause uses the subjunctive.

Here, Cum responsum dubium est is a straightforward present-time clause: when the answer is uncertain. Latin often uses the indicative with cum for simple temporal meaning.

You are more likely to see cum + subjunctive when the clause gives background, cause, or concession in a more literary way.

So here:

• cum ... est = a simple when clause
• no special subjunctive nuance is being emphasized

Because it is the subject of est.

In responsum dubium est:

• responsum = the thing being described
• est = is
• dubium = uncertain

So responsum must be nominative singular.

Because dubium agrees with responsum.

• responsum is neuter singular
• the adjective describing it must also be neuter singular
• so we get dubium

If the noun were masculine, you might expect dubius. If feminine, dubia.

This is a very common Latin pattern: a verb of asking, urging, commanding, or persuading + ut + subjunctive.

So:

• magistra rogat = the teacher asks
• ut discipula ... dicat = that the student say ...

This is often called an indirect command or substantive clause of command.

Because it is inside the ut clause after rogat.

After verbs like rogo, moneo, impero, hortor, Latin commonly uses:

• ut
  • subjunctive for a positive command/request
• ne
  • subjunctive for a negative command/request

So rogat ut ... dicat means she asks that ... say / more natural English: she asks ... to say.

Dicat is present subjunctive active, third person singular.

It is present because the request is happening at the same time as the main verb:

• magistra rogat = the teacher asks
• discipula ... dicat = that the student say

This follows normal sequence of tenses:

• main verb in a primary tense (rogat, present)
• subordinate subjunctive often in the present for action happening at the same time or after

Because discipula is the subject of dicat in the subordinate clause.

In ut discipula sinceram sententiam aperte dicat:

• discipula = the one doing the speaking
• sententiam = what is being spoken/stated

So:

• discipula is nominative
• sententiam is accusative

Because it is the direct object of dicat.

The verb dico can take something that is said or stated as its object. Here that thing is sinceram sententiam.

So:

• discipula = subject
• dicit/dicat = verb
• sententiam = direct object

Because sinceram is an adjective modifying sententiam, and it must agree with it in:

• gender: feminine
• number: singular
• case: accusative

So:

• sententia = feminine singular noun
• as a direct object, it becomes sententiam
• the adjective becomes sinceram to match it

They do different jobs.

• sinceram is an adjective: it describes the noun sententiam
• aperte is an adverb: it describes the verb dicat

So the sentence is not just saying a sincere opinion, but also saying that it should be spoken openly/plainly.

A useful contrast:

• sincera sententia = a sincere opinion
• aperte dicere = to speak openly

Latin usually does not copy the English infinitive pattern after ask in this kind of sentence.

English often says:

• The teacher asks the student to say ...

Latin instead commonly says:

• magistra rogat ut discipula ... dicat
• literally, the teacher asks that the student say ...

So this is a place where Latin and English structure the idea differently.

Yes, in a way.

The sentence has:

1. a cum clause: Cum responsum dubium est
2. the main clause: magistra rogat
3. an ut clause depending on rogat: ut discipula sinceram sententiam aperte dicat

So the overall structure is:

• When X is the case, the teacher asks that Y happen.

This kind of layering is very normal in Latin.

Latin word order is much more flexible because endings show each word’s function.

For example:

• responsum is clearly nominative
• sententiam is clearly accusative
• discipula is clearly nominative
• dicat is clearly the verb of the subordinate clause

That means Latin can arrange words for emphasis or style instead of relying on fixed word order as much as English does.

A very literal order here is:

• When the answer is uncertain, the teacher asks that the student speak a sincere opinion openly.

English usually rearranges that into something smoother.

They are related in meaning, but not identical.

• responsum means answer or response
• sententia means opinion, view, judgment, or thought

So the sentence suggests something like this:

• if the existing answer is uncertain,
• the teacher asks the student to state her own sincere opinion

That contrast helps explain why two different nouns are used.

Yes. Latin often leaves out subject pronouns or even subject nouns when they are clear from context.

So Latin could have said something like:

• magistra rogat ut sinceram sententiam aperte dicat

and the verb ending -at would already show he/she/it.

But including discipula makes the subject explicit and avoids ambiguity.