We use shot form to show that action is made over a subject. For example: "машина была припарковАНа возле сада" - "The car has been parked near a garden" and long form: "припарковАННая машина была возле сада" - "The parked car was near a garden" Other cases need to be considered separately ;)

So I'd like to write some basic rules concerning the short form of adjectives: Russian adjectives have long and short form. To be more precise, only qualitative adjectives may have both long and short forms (лёгкий - лёгок, красивый - красив). In today's conversational Russian the usage of long adjectives if preferred. However, you will most likely have to use the short form of an adjective in the end of a sentence. For example: Эта комната занятая.-long form Эта комната занята.(This room is occupied.)- short form Short adjectives usually describe temporary qualities, as opposed to long adjectives that refer to constant and general qualities. For example, we say: Ольга -счастливая девушка.(Olga is a happy girl.) - constantly Вчера вечером она была очень счастлива.(She was very happy last night.) - temporarily Short adjectives can also refer to qualities with respect to a particular person, thing or circumstances. For example: Папин костюм сыну велик. (The father's suit is big for the son.) Some Russian adjectives do not have a short form.

The rule of the using of short adjectives is not so easy in russian . But I want to point out the main rule: For example:how is it right to say about a boy with a weak health: Мальчик болЕН(short form) or Мальчик больНОЙ(full form)?=A boy is sick. Мальчик больНОЙ -- means that the boy is permanently sick,or has problems with his health permanently. Мальчик болЕН -- means that the boy is temporary sick,and the problems with his health is temporary. So, the difference is in the time description of the adjectives. When we want to say the full form of adjective while talking about the temporary situation, we should specify when the boy is sick or has problems,e.g. Мальчик СЕГОДНЯ(today) больНОЙ. In this case СЕГОДНЯ(today) point out that the situation is temporary.

Будь спокоен, краток, непогрешим - when you wish someone something, for example. Give us sentenses, your examples and we will see.