Η επιστήμη χρειάζεται έρευνα.

Η is the feminine singular definite article, equivalent to the in English.

In Η επιστήμη χρειάζεται έρευνα, it goes with επιστήμη because:

• επιστήμη is a feminine noun
• it is singular
• it is the subject of the sentence

So Η επιστήμη means science or the science, depending on context. In Greek, the definite article is used more often than in English, especially with general or abstract nouns.

Greek often leaves out the article when talking about something in a general or indefinite way.

So:

• η έρευνα = the research
• έρευνα = research / some research

In this sentence, έρευνα is being used as a general, uncountable idea, so no article is needed. This is very natural in Greek.

χρειάζεται is the 3rd person singular present tense of the verb χρειάζομαι / χρειάζω in modern usage meaning to need.

Here it matches the subject Η επιστήμη because επιστήμη is singular:

• η επιστήμη χρειάζεται = science needs

So the verb ending -εται here corresponds to he/she/it needs or needs with a singular noun subject.

It looks like a middle/passive form because of the ending -εται, and historically it is connected with that system. But in modern Greek, χρειάζομαι / χρειάζεται often functions with an active meaning: need.

So even though it may look passive to a learner, in practice:

• Χρειάζομαι βοήθεια = I need help
• Η επιστήμη χρειάζεται έρευνα = Science needs research

This is something worth getting used to: some Greek verbs have passive-style endings but active meanings.

It is in the accusative case, because it is the direct object of the verb χρειάζεται.

The sentence structure is:

• Η επιστήμη = subject
• χρειάζεται = verb
• έρευνα = object

For this noun, the nominative and accusative singular happen to look the same:

• nominative: η έρευνα
• accusative: την έρευνα

When there is no article, you just see έρευνα, so the case is understood from its role in the sentence.

The accent mark shows where the word is stressed.

• επιστήμη is stressed on the last syllable: e-pi-sti-MI
• χρειάζεται is stressed on -ά-: chrei-A-ze-tai
• έρευνα is stressed on the first syllable: E-rev-na

Stress is very important in Greek, because it is part of the standard spelling and pronunciation.

Yes. Greek word order is more flexible than English because case endings help show grammatical roles.

The neutral, straightforward order here is:

• Η επιστήμη χρειάζεται έρευνα.

But other orders are possible for emphasis, for example:

• Έρευνα χρειάζεται η επιστήμη. = It is research that science needs.

That said, for learners, the original order is the safest and most natural to produce first.

Yes, but the singular here is being used in a general, abstract sense, much like English science.

So:

• Η επιστήμη χρειάζεται έρευνα. = science as a field or concept
• Οι επιστήμες χρειάζονται έρευνα. = the sciences need research

The singular is very natural when speaking about science as a whole.

Usually yes, but it can sometimes have a slightly broader or more formal sense related to systematic knowledge or a field of learning.

In most everyday and academic contexts:

• επιστήμη = science
• plural επιστήμες = sciences

So in this sentence, it matches English science very well.

It could be correct, but it means something more specific.

Compare:

• Η επιστήμη χρειάζεται έρευνα. = Science needs research in general
• Η επιστήμη χρειάζεται την έρευνα. = Science needs the research, meaning some specific research already known from context

So the version without the article sounds more general and is the better choice for a broad statement.

A simple pronunciation guide is:

i epi-STI-mi chri-A-ze-te E-rev-na

More approximately:

• Η = ee
• επιστήμη = epi-STEE-mee
• χρειάζεται = hree-AH-ze-te
• έρευνα = EH-rev-na

The χ sound in χρειάζεται is not like English ch in chair. It is a harsher sound, somewhat like the h in huge for many speakers, or like German ch in ich for others depending on the vowel that follows.