A. J. Lohwater's Russian-English Dictionary of the Mathematical Sciences

заниматься,   "to study"
present		я занимаюсь ты занимаешься он занимается		мы занимаемся вы занимаетесь они занимаются
past		занимался, занималась, занималось, занимались

4. The imperative mood. The imperative form of a verb is also known as the "command": "Solve the problem, read your paper." The imperative, as in English, has the understood subject "you." In Russian, since there are two "you's," there are two imperative forms, one for ты and one for вы: Делай работу! Делайте работу! "Do the work!" singular and plural; Расти! Растите! "Grow!" singular and plural. The singular endings are -и or -й after a vowel; the plural endings are the same but with an additional -те. Reflexive verbs, those ending in the particle -ся retain this particle at the end of the imperative: занимайтесь from заниматься, "study."

5. The conditional mood. The conditional is formed by following the past tense form of the verb with the particle бы.

Он читал бы. → He should have read. He would have read.

6. Participles. Participles are verb forms which act as adjectives. They retain the quality of transitivity if the verb is transitive, intransitivity if the verb is intransitive. A participle also retains the aspect of the verb from which it is formed.

a. Participles may be present or past tense:

студент, читающий доклад → a student who read/is reading a paper

студент, читавший доклад → a student who read/was reading/had been reading a paper

Note the adjectival endings on the participles. Participles agree in gender, number, and case with the nouns they modify.

b. Participles are also active or passive. An active participle describes the noun which is the agent of the action, whereas a passive participle describes the noun which is the object of the action.

студент, прочитавший доклад → the student who had read the paper

статья, прочитанная студентом → the article read by the student

Note that the agent of the passive participle is in the instrumental case. Passive participles are formed only from transitive verbs (those which take direct objects); reflexive verbs, which are intransitive, thus do not form passive participles.

c. Formation of the participle.

i. Present active participles Add the suffix plus adjectival endings to the present-tense stem.

1st-conjugation verbs add -ущ-, -ющ-: читать – чита/ют – чита/ющ/ий, читающий

2nd-conjugation verbs add -ащ-, -ящ-: говорить – говор/ят – говор/ящ/ий, говорящий

ii. Past active participles Add the suffix plus adjectival endings to the past-tense stem.

If the stem ends in a vowel, add -вш-: читать – чита/л – чита/вш/ий, читавший

If the stem ends in a consonant, add -ш-: нес/ти – нёс – нёс/ш/ий, нёсший

iii. Present passive participles Add the suffix plus adjectival endings to the stem of the present tense.

1 st-conjugation verbs add -ем-: читать – чита/ют – чита/ем/ый, читаемый рисовать – рису/ют – рису/ем/ый, рисуемый

2nd-conjugation verbs add -им-: любить – люб/ят – люб/им/ый, любимый

iv. Past passive participles Add the suffix plus adjectival endings to past-tense stem.

-нн-, or -т- if stem ends in a vowel: прочитать – прочита/л – прочита/нн/ый, прочитанный взять – взя/л – взя/т/ый, взятый

-енн- if stem ends in a consonant or -и-: принести – принёс – принес/ённ/ый, принесённый изучить – изучи/л – изуч/енн/ый, изученный ⁷

v. Participles from reflexive verbs Participles ending in the reflexive particle always take the -ся form.

vi. Short-form participles Because participles are adjectival in form, they may occur as short-form participles. However, only passive participles have both the long and short forms; active participles occur only in the long form. Short-form participles are used as the predicate of a passive construction. They consist of stem plus suffix plus short-form adjective endings. Like short-form adjectives, they are only used as predicate adjectives, and so they do not decline. The suffixes -н-, -ен- (-ён-), and -т- are added to the stem:

прочитать – прочитан

решить – решён

занять – занят