La inspektoro kontrolas la plafonon.

Because Esperanto uses la for the, and each definite noun normally gets its own article.

So:

• la inspektoro = the inspector
• la plafonon = the ceiling

Just like in English, you say the inspector checks the ceiling, not the inspector checks ceiling.

Unlike English, Esperanto has only one definite article: la. It does not change for gender, number, or case.

The final -n marks the direct object. That means plafonon is the thing being checked.

• La inspektoro = the inspector (subject: the one doing the action)
• kontrolas = checks / is checking
• la plafonon = the ceiling (direct object: the thing receiving the action)

This -n ending is called the accusative ending.

So:

• plafono = ceiling
• plafonon = ceiling as the direct object

Because inspektoro is the subject, not the direct object.

In this sentence, the inspector is performing the action, so it stays in the basic noun form:

• inspektoro = inspector

Only the noun receiving the action gets -n:

• plafonon = the ceiling

In Esperanto, nouns end in -o.

So:

• inspektoro = inspector
• plafono = ceiling

This is one of the most important patterns in Esperanto. If you see a word ending in -o, it is a noun.

Other very common endings are:

• -a for adjectives
• -e for adverbs
• -i for infinitive verbs
• -as for present-tense verbs

Because -as is the Esperanto ending for the present tense.

So kontrolas means:

• checks
• is checking
• sometimes simply does check, depending on context

Esperanto does not change the verb ending depending on the subject. So:

• mi kontrolas = I check
• vi kontrolas = you check
• li kontrolas = he checks
• ili kontrolas = they check

The verb stays kontrolas every time.

It can mean either one.

In Esperanto, the simple present tense often covers both:

• checks
• is checking

So La inspektoro kontrolas la plafonon could mean:

• The inspector checks the ceiling
• The inspector is checking the ceiling

Usually the context tells you which one is meant.

Yes, Esperanto word order is fairly flexible because the -n ending helps show what is the direct object.

The neutral, most common order is:

• La inspektoro kontrolas la plafonon.

But you could also say:

• La plafonon kontrolas la inspektoro.

This still means The inspector checks the ceiling, because plafonon has -n, so we know it is the object.

That said, the standard subject–verb–object order is usually best for learners.

Yes, grammatically you could, but the meaning changes slightly.

• la plafonon = the ceiling (a specific ceiling)
• plafonon = a ceiling or ceiling in a less specific sense

So:

• La inspektoro kontrolas la plafonon = The inspector checks the ceiling.
• La inspektoro kontrolas plafonon = The inspector checks a ceiling / is checking ceiling surface in a less definite sense.

Esperanto has no separate word for a/an. Often the noun simply appears without la.

A rough guide for English speakers:

• la = lah
• inspektoro = in-spek-TO-ro
• kontrolas = kon-TRO-las
• la = lah
• plafonon = pla-fo-NON

A few useful pronunciation points:

• Esperanto vowels are very regular.
• r is usually rolled or tapped.
• Stress is on the second-to-last syllable.

So the stressed syllables are:

• inspekTOro
• konTROlas
• plafoNON

Yes, they are words that look familiar to English speakers because Esperanto uses many international roots.

• inspektoro is clearly related to inspector
• kontroli is related to control/check
• plafono is related to words like plafond in French and may be less obvious to English speakers

This is very common in Esperanto: many words come from roots that are recognizable if you know English or other European languages.

The dictionary forms are:

• kontroli = to check / to inspect
• plafono = ceiling

Why?

• Verbs are listed in the infinitive form, ending in -i
• Nouns are listed in the basic form ending in -o, without the accusative -n

So when looking up words, remove grammatical endings:

• kontrolas → kontroli
• plafonon → plafono