Hace media hora que ella investiga el decorado.

This is a very common Spanish structure for saying that something started some time ago and is still continuing now.

Hace + time expression + que + present tense

So:

Hace media hora que ella investiga el decorado
means roughly: She has been investigating the set for half an hour.

Literally, hace means it makes or it has been, but in English we normally translate the whole structure as for or has been ... for.

Because Spanish often uses the present tense where English uses the present perfect continuous.

In English, we say:

She has been investigating...

In Spanish, with this time-expression pattern, it is normal to say:

Hace media hora que investiga...

So even though the Spanish verb is in the present, the meaning is still an action that began in the past and continues now.

This is one of those places where Spanish and English do not match tense-for-tense.

Media hora means half an hour.

• media = half
• hora = hour

So:

Hace media hora que... = for half an hour now...

Be careful: hace media hora can also mean half an hour ago in other contexts. The rest of the sentence tells you which meaning is intended.

Here, que is part of the fixed structure hace + time + que + verb.

It links the time expression to the action:

Hace media hora que investiga...

You generally need que in this pattern.

Compare:

• Hace media hora que investiga el decorado. = She has been investigating the set for half an hour.
• Empezó a investigar el decorado hace media hora. = She started investigating the set half an hour ago.

So que helps build the specific ongoing duration structure.

Usually, no.

Spanish often drops subject pronouns because the verb ending already shows the person:

investiga = he/she investigates

So the sentence could naturally be:

Hace media hora que investiga el decorado.

Including ella may be used for:

• emphasis
• contrast
• clarity, if it is important to specify that it is she

For example:

• Él no; ella hace media hora que investiga el decorado.

Without a special reason, Spanish often prefers leaving ella out.

El decorado usually means the set, the scenery, or the stage/film set.

In Spain, decorado is commonly used for the physical set used in:

• theatre
• television
• cinema

It is not always the same as decoración, which is more like decoration or interior decor in a broader sense.

So in this sentence, el decorado most likely means something like the set design or the stage/film set.

Yes, you could say:

Hace media hora que está investigando el decorado.

But in this kind of sentence, Spanish very often uses the simple present:

Hace media hora que investiga el decorado.

The version with está investigando puts more focus on the action being in progress right now. The simple present is often more natural and lighter in this structure.

So both are possible, but investiga is very normal here.

You tell from the structure around it.

1. Ongoing action: for half an hour

If you have:

Hace media hora que + present tense

it means the action started half an hour ago and is still continuing.

Example:
Hace media hora que investiga el decorado.
= She has been investigating the set for half an hour.

2. Past point in time: half an hour ago

If hace media hora simply refers to when something happened, it means half an hour ago.

Example:
Empezó a investigar el decorado hace media hora.
= She started investigating the set half an hour ago.

So the key is whether the sentence is showing duration up to now or just a past moment.

Yes. A very common alternative is:

Lleva media hora investigando el decorado.

This also means:

She has been investigating the set for half an hour.

Spanish has several natural ways to express this idea:

• Hace media hora que investiga el decorado.
• Lleva media hora investigando el decorado.
• Desde hace media hora, investiga el decorado.

Of these, lleva + time + gerund is especially common in everyday Spanish.

It is grammatically correct and understandable, but it can sound slightly formal or textbook-like, especially because of investiga el decorado, which is not a very everyday combination.

In real-life Spanish, people might more often say:

• Lleva media hora investigando el decorado.
• Lleva media hora examinando el decorado.
• Hace media hora que está mirando el decorado.

So the grammar is good, but the exact wording may feel a little more like an exercise sentence than casual speech.