The complement

1. What is it?

A complement is a part of a sentence, that tells what, or what kind, the subject is or isn't. The complement can be either a noun or an adjective. The sentence verb is always "olla."

Finnish English
Ihminen on erehtyväinen. A person is fallible.
Hän ei ole enää kansanedustaja. He isn't a member of parliament anymore.
Olut oli lämmintä. The beer was warm.
Lukeminen on hauskaa. Reading is fun.
Ovatko nuo turistit kiinalaisia? Are those tourists Chinese?
Hänen kätensä ovat sirot. Her hands are graceful.
Suomalaiset ovat hiljaisia. Finns are quiet.


2. What form is it in?

2.1 If the subject is a concrete thing and singular, the complement is in the singular nominative.

Finnish English
Englannin parlamentti on kaksihuoneinen. The English parliament is two-roomed.
Ohjelma ei ole valmis. The program is not finished.
Elokuva oli sekava. The movie was confusing.
Päivä ei ollut aurinkoinen. The day wasn't sunny.

2.2 When the subject is a plural word (pair or entity, which is expressed always or almost always in plural) or a body part that comes in a pair, the complement is in the plural nominative.

Finnish English
Mäyräkoiran jalat ovat lyhyet. A dachshund's legs are short.
Hänen kyntensä olivat pitkät. Her nails were long.
Sinun hampaasi ovat loistavan valkoiset. Your teeth are wonderfully white.
Katjan lakkiaiset olivat vauhdikkaat. Katja's graduation was brisk.
Näyttelyn avajaiset olivat juhlalliset. The exhibition's opening was grand.
Sukat ovat kuluneet. The socks are worn-down.

2.3 If the plural word doesn't mean one pair or entity, the complement is in the plural partitive.

Finnish English
Kengät ovat kalliita. Shoes are expensive (in general).
Kengät ovat kalliit. The shoes are expensive (a specific pair of shoes).
Nämä kengät ovat italialaisia. These shoes are Italian (a brand of shoes).
Nämä kengät ovat italialaiset. These shoes are Italian (a specific pair of shoes).
Valokuvat olivat onnistuneita. The pictures were successful.
Tauot olivat liian lyhyitä. The breaks were too short.
Te olette niin nuoria. You (plural) are so young.
He eivät ole suomalaisia. They aren't Finns.
Kaikki olivat uusia opiskelijoita. Everyone was a new student.
Nuo naiset ovat tulkkeja. Those women are interpreters.

2.4 When the subject is mass noun or an abstract noun, the complement is in the singular partitive.

Finnish English
Ydinjäte on vaarallista. Nuclear waste is dangerous.
Se on radioaktiivista. It's radioactive.
Tupakointi on epäterveellistä. Smoking is unhealthy.
Vaatteiden silittäminen on ikävää. The ironing of clothes is unpleasant.
Veneily on ihanaa. Boating is lovely.
Onko tämä pusero silkkiä? Is this sweater made of silk?
Ei, tämä pusero on puuvillaa. No, this sweater is made of cotton.
Onko tämä pusero silkkiä? Is this sweater made of silk?


3. Examples

Vesi on kylmää.
Sinun kätesi on kylmä.
Sinun kätesi ovat kylmät.
Minun käteni eivät ole kylmät.

Explanation:
Vesi on kylmää -> the complement has to be partitive, because the subject is a mass noun.

Sinun kätesi on kylmä -> the complement is in the nominative singular, because the subject is a concrete thing, and singular.

Sinun kätesi ovat kylmät -> the complement is in the plural nominative, because the subject is a plural word, and a bodypart that comes in a pair.

Minun kätesi eivät ole kylmät -> Making this sentence negative doesn't make the complement become partitive because hands always come in pairs!