Finite forms of the verb can only be used in the function of the predicate and possess five grammar categories - Tense, Voice, Person, Number and Mood.
He has been reading this book for ages.
Он читает эту книгу вечно.
Non-finite forms cannot perform the function of the predicate and possess two grammar categories only - Tense and Voice. But their tenses look quite different from those of finite forms.
All non-finite forms have a double nature – on the one hand they are verbal parts of speech possessing some verbal characteristics but, on the other hand they have some likeness to nominal parts of speech: this likeness is manifested in their synthetic functions.
The verbal characteristics of non-finite forms are the following:
The non-finite forms of transitive verbs can take a direct object.
Reading this book I learnt a lot of interesting things.
Читая эту книгу, я узнал много интересного.
Learning foreign languages is quite a difficult process.
Изучение иностранного языка - это достаточно трудный процесс.
But: The learning of foreign…
I like to read detective stories.
Я люблю читать детективы.
Non-finite forms can be modified by an adverb.
I don't like driving slowly.
Я не люблю медленно ездить.
Walking slowly along the street he was thinking about the forthcoming meeting with his father.
Медленно прогуливаясь вдоль улицы, он думал о приближающейся встрече с отцом.
I hate to speak loudly.
Я не люблю громко разговаривать.
Non-finite forms possess the categories of tense and voice; Participle I and the Gerund have two tenses and two voices and the Infinitive has four tenses in the active voice and two tenses in the passive voice.
The forms of Participle I and the Gerund.
Active Passive Indefinite writing being written Perfect having written having been written
The forms of the Infinitive.
Active Passive Indefinite to write to be written Continuous to be writing Perfect to have written to have been written Perfect Continuous to have been writing
The tenses of non-finite forms are not absolute but relative. It means that the action expressed by a non-finite form of the verb is compared with the action expressed by the finite form of the verb and if they are simultaneous, the Indefinite form is used (for the Infinitive the Indefinite or Continuous form), if the action expressed by a non-finite form is prior to the action expressed by the finite form, the Perfect form is used (the Perfect Continuous form of the Infinitive denotes an action which began before the action expressed by the finite form, has been going on for a certain period of time and still going on when the other action begins).
Listening to this music I remembered my first meeting with him.
Слушая эту музыку я вспоминаю нашу с ним первую встречу.
Having written a report on my business trip I took it to the accounting department.
Написав отчет о командировке, я отнес его в бухгалтерию.
I do not approve of your being late for the lessons so often.
Я не одобряю ваши частые опоздания на занятия.
I do not approve having discussed this question in the presence of the child.
Я не одобряю обсуждение таких вещей в присутствии детей.
He is said to know this subject well.
Говорят, что он хорошо знает этот предмет.
He is said to be working at his doctorate.
Говорят, что он работает над докторской.
He is said to have left for Switzerland.
Говорят, что он уехал в Швейцарию.
She is said to have been working at her new novel for several years.
Говорят, она работает над своим новым романом уже несколько лет.
The likeness to nominal parts of speech is manifested in the functions of non-finite forms.
The Participle possesses some likeness to the adjective and the adverb because its main functions are the attribute and the adverbial modifier.
The girl sitting at the piano is his cousin.
Девушка, сидащая за пианино, был его двоюродной сестрой.
He gave me an article translated from an English medical journal.
Он дал мне переведенную статью из английского медицинского журнала.
Having corrected the student's papers she switched on the TV-set.
Проверив работы студентов она включила телевизор.
If dressed properly she would look pretty.
Правильно одетая, она бы выглядела хорошо.
The Gerund and the infinitive possess some likeness to the noun because their main functions are the subject, the object and the predicative (the nominal part of the Compound Nominal Predicate).
Smoking is bad for ones health.
Курение вредит здоровью.
I am fond of traveling.
Я люблю путешествовать.
His hobby is collecting coins.
Его хобби - коллекционирование монет.
It is necessary to find him at once.
Нужно немедленно его найти.
I'd like to learn to drive.
Мне бы понравилось учиться водить.
My only wish is to help you.
Мое единственное желание - помогать тебе.