Ελέγχω το δείγμα στο εργαστήριο.

Greek often leaves out subject pronouns when they are not needed. The verb form ελέγχω already tells you the subject is I.

The ending -ω is the typical 1st person singular ending in the present tense, so:

ελέγχω = I check / I examine / I inspect

If you want, you can add εγώ for emphasis, but it is usually unnecessary: Εγώ ελέγχω το δείγμα στο εργαστήριο. = I am checking the sample in the laboratory.

Ελέγχω is in the present tense.

Depending on context, the Greek present can mean:

• I check
• I am checking
• I do check

So the sentence can describe:

• something happening right now
• something done regularly or generally

Context tells you which meaning is intended.

Το δείγμα is the direct object of the verb, meaning it is the thing being checked.

In Modern Greek, direct objects usually take the accusative case.
Here:

• το = the
• δείγμα = sample

So το δείγμα means the sample in the accusative.

Because δείγμα is a neuter noun, the article is το.

Because δείγμα is a neuter noun, and many neuter nouns have the same form in the nominative and accusative singular.

So:

• nominative: το δείγμα
• accusative: το δείγμα

This is very common with neuter nouns in Greek, so even though it is the object of the sentence, the noun itself looks unchanged.

Στο is a contraction of:

σε + το = στο

So literally it is something like:

• in the
• at the
• sometimes to the, depending on context

In this sentence, στο εργαστήριο means in the laboratory or at the laboratory/lab.

The preposition σε in Modern Greek normally takes the accusative case, and here it combines with το to form στο.

So:

• σε το εργαστήριο → στο εργαστήριο

Since εργαστήριο is also a neuter singular noun, it appears as:

• το εργαστήριο = the laboratory
• στο εργαστήριο = in/at the laboratory

Again, because it is neuter, its form does not visibly change here.

It can mean different things in different sentences, because σε can cover in, at, or to.

In this sentence, with Ελέγχω το δείγμα, the natural meaning is in the lab or at the lab, because it describes the location where the checking happens.

So: Ελέγχω το δείγμα στο εργαστήριο.
= I check the sample in/at the laboratory.

If motion were involved, στο could mean to the:

• Πηγαίνω στο εργαστήριο. = I am going to the laboratory.

The basic order is:

Verb + Object + Place

So:

• Ελέγχω = verb
• το δείγμα = object
• στο εργαστήριο = place/location phrase

Greek word order is more flexible than English word order, because case endings and articles help show the grammatical roles.

Yes. Greek allows more flexibility than English, especially for emphasis or style.

For example, all of these are possible:

• Ελέγχω το δείγμα στο εργαστήριο.
• Στο εργαστήριο ελέγχω το δείγμα.
• Το δείγμα ελέγχω στο εργαστήριο.

They all keep roughly the same core meaning, but the emphasis changes:

• Στο εργαστήριο... emphasizes the place
• Το δείγμα... emphasizes the object

The version you were given is a very natural, neutral sentence.

You can tell from the article το.

In singular Greek articles:

• ο = masculine
• η = feminine
• το = neuter

So:

• το δείγμα → δείγμα is neuter
• το εργαστήριο → εργαστήριο is neuter

Also, many neuter nouns end in:

• -μα like δείγμα
• -ιο like εργαστήριο

Those endings are very commonly neuter.

A rough pronunciation is:

E-LENG-ho to THEEG-ma sto er-ga-STEE-rio

A few helpful notes:

• γχ in ελέγχω is pronounced roughly like ngh / nkh, depending on accent and speed
• δείγμα sounds roughly like THEEG-ma, because δ in Modern Greek is like th in this
• ει is pronounced like ee
• the stress falls on:
  • ε in Ελέγχω
  • δεί in δείγμα
  • στή in εργαστήριο

It can have a range of meanings depending on context, such as:

• check
• inspect
• examine
• verify
• sometimes control in certain contexts

So Ελέγχω το δείγμα could mean something like:

• I check the sample
• I examine the sample
• I inspect the sample

The exact English choice depends on what kind of checking is meant.

No, because εργαστήριο is neuter, so it takes το.

The contracted forms of σε + article are:

• στον = σε + τον, for masculine
• στη(ν) = σε + τη(ν), for feminine
• στο = σε + το, for neuter

Since εργαστήριο is neuter, the correct form is:

στο εργαστήριο

The dictionary forms are:

• ελέγχω = to check / examine / inspect
• το δείγμα = the sample
• το εργαστήριο = the laboratory / lab

For nouns, Greek dictionaries usually give the noun together with its article, because the article tells you the gender:

• το δείγμα
• το εργαστήριο

That is very useful to memorize from the start.