Uzorak krvi je iz vene.

to be

Breakdown of Uzorak krvi je iz vene.

• iz: from
• uzorak krvi: a blood sample
• vena: a vein

Questions & Answers about Uzorak krvi je iz vene.

Why is it krvi and not krv?

Because krvi is the genitive singular form of krv (blood).

In uzorak krvi, the first noun uzorak (sample) is followed by another noun in the genitive to show what kind of sample it is or a sample of what.

So:

• uzorak = sample
• krv = blood
• uzorak krvi = a blood sample / literally sample of blood

This is a very common pattern in Serbian:

• čaša vode = a glass of water
• flaša vina = a bottle of wine
• kraj grada = the edge of the city

Why is it vene and not vena?

Because iz requires the genitive case, and the genitive singular of vena (vein) is vene.

So:

• vena = vein
• iz vene = from a vein

This is one of the basic preposition-case combinations you need to learn in Serbian:

• iz + genitive = out of / from
• od + genitive = from, of
• do + genitive = to, until

So in this sentence, iz vene means from a vein.

What exactly does je mean here?