Virus itu berbahaya.

Malay often leaves out the verb to be in simple sentences like this.

So instead of saying Virus itu is dangerous, Malay simply says:

• Virus itu berbahaya

This is very common when a noun is followed by an adjective or another noun phrase.

Examples:

• Rumah itu besar = The house is big
• Dia guru = He/She is a teacher

Itu usually means that, but in many sentences it also works a bit like the, marking something as specific or already known.

So virus itu can mean:

• that virus
• or, depending on context, the virus

In real use, Malay itu is often more flexible than English that.

In Malay, demonstratives like ini (this) and itu (that) normally come after the noun.

So:

• virus itu = that virus
• rumah ini = this house

This is different from English, where this/that comes before the noun.

Yes. Berbahaya means dangerous and functions as an adjective.

In Virus itu berbahaya, it describes the subject virus itu.

So the sentence structure is:

• Virus itu = subject
• berbahaya = predicate adjective

The word berbahaya is built from bahaya (danger) plus the prefix ber-.

In this word, the whole form berbahaya means dangerous or harmful. For a learner, it is best to treat berbahaya as a complete vocabulary item.

Even though ber- often has other functions in Malay, you do not need to analyze it too deeply here. Just learn:

• bahaya = danger
• berbahaya = dangerous

You usually should not use adalah before an adjective like berbahaya in a normal sentence.

The natural sentence is:

• Virus itu berbahaya

Adalah is more formal and is mainly used before nouns or in formal definitions and written styles. With adjectives, everyday Malay normally leaves it out.

So for learners, the safest choice here is simply:

• Virus itu berbahaya

You would use tidak, because berbahaya is an adjective.

• Virus itu tidak berbahaya = That/The virus is not dangerous

Malay usually uses:

• tidak for verbs and adjectives
• bukan for nouns and noun phrases

So:

• Virus itu tidak berbahaya = correct
• Virus itu bukan berbahaya = not the normal choice here

Yes, you can, but the meaning may become less specific.

• Virus itu berbahaya = That/The virus is dangerous
• Virus berbahaya can be interpreted differently depending on context, such as Viruses are dangerous or A virus is dangerous, and it can also sound like part of a noun phrase in some situations.

So if you want to refer to one specific virus, itu helps make that clear.

That is true, but this sentence is not just a noun phrase. It is a full sentence.

Malay adjectives often come after nouns in noun phrases:

• virus berbahaya = a dangerous virus

But in your sentence:

• Virus itu is the subject
• berbahaya is the predicate

So the pattern is really:

• subject + predicate

That is why berbahaya comes after virus itu.

They are different structures.

• virus berbahaya = dangerous virus
  This is a noun phrase, not a complete statement by itself in many contexts.

• virus itu berbahaya = that/the virus is dangerous
  This is a full sentence.

So adding itu helps make virus itu a complete subject, and berbahaya becomes what is being said about it.

By itself, virus does not show singular or plural. Malay nouns often do not change form for number.

So virus can mean:

• virus
• viruses

Context tells you which one is meant.

In Virus itu berbahaya, the presence of itu strongly suggests a specific one:

• that/the virus

If you needed to make plurality very clear, Malay can use other words or context, and sometimes reduplication in some cases, though that is less natural with every noun in every situation.

A simple learner-friendly pronunciation is:

• vee-roos ee-too ber-ba-HA-ya

A few notes:

• virus is a borrowed word and sounds fairly similar to English, but with a clearer vowel sound
• itu = ee-too
• berbahaya has four main parts: ber-ba-ha-ya

The final ya sounds like yah, not like English yay.

Yes, if you want to mean this instead of that.

• Virus ini berbahaya = This virus is dangerous
• Virus itu berbahaya = That/The virus is dangerous

Again, the demonstrative comes after the noun:

• virus ini
• virus itu