Learn Hardcore Indonesian: Piring kotor harus dicuci.

harus means “must” or “have to.” It expresses necessity or obligation. In Indonesian syntax, harus always precedes the main verb or verb phrase, regardless of whether that verb is active or passive.
Examples:

harus membuat (must make)
harus dicuci (must be washed)

Why is the verb dicuci used instead of mencuci?

dicuci is the passive form of cuci (to wash). The prefix di- marks that the action is done to the subject (the plates), not by the subject. If you wanted the sentence in active voice (plate washer as the subject), you’d use mencuci.

Passive: Piring kotor harus dicuci. (Dirty plates must be washed.)
Active: Saya harus mencuci piring kotor. (I must wash the dirty plates.)

Is this sentence in the passive voice? How can you tell?

Yes. Indicators:
• The verb has the di- prefix (dicuci).
• There’s no explicit agent doing the washing.
• The “object” (piring kotor) comes before the verb.
Structure: [Object] + harus + di-verb = passive necessity.

Why is there no subject like “I” or “they” in Piring kotor harus dicuci?

Indonesian often omits the subject when:
• It’s a general statement (everybody or no one in particular).
• The doer is obvious or not important.
To specify the subject/agent, either switch to active voice or add oleh + agent:

Piring kotor harus dicuci oleh ibu. (The dirty plates must be washed by mom.)
Ibu harus mencuci piring kotor. (Mom must wash the dirty plates.)

Why is the adjective kotor placed after the noun piring?

In Indonesian, adjectives follow the nouns they modify.
Pattern: [Noun] + [Adjective]
Examples:

rumah besar (house big → big house)
anak pintar (child clever → clever child)

How can I say this in the active voice?

Introduce a subject and use the active verb mencuci:
• Saya harus mencuci piring kotor. (I must wash the dirty plates.)
• Kita harus mencuci piring kotor. (We must wash the dirty plates.)
Subject + harus + mencuci + object.

How do I specify who must wash the plates without changing voice?

Add the agent after oleh in the passive sentence:
• Piring kotor harus dicuci oleh kakak. (The dirty plates must be washed by older sibling.)
“oleh” = by

How do you talk about past or future actions since Indonesian verbs aren’t inflected for tense?

Use time adverbs or aspect words:
• Past:
– Kemarin piring kotor harus dicuci. (Yesterday dirty plates had to be washed.)
– Piring kotor sudah dicuci. (The dirty plates have been washed.)
• Future:
– Besok piring kotor harus dicuci. (Tomorrow dirty plates must be washed.)
• Not yet / already:
– Piring kotor belum dicuci. (The dirty plates haven’t been washed yet.)
– Piring kotor sudah dicuci. (The dirty plates are already washed.)