Theoretical aspects of the studied language

Simple and progressive

The progressive (or continuous) aspect is expressed with a form of be together with the present participle of the verb. Thus present progressive (present continuous) constructions take forms like am writing, is writing, are writing, while the past progressive (past continuous, also called imperfect) is was writing, were writing. There is a progressive infinitive (to) be writing and a progressive subjunctive be writing. Other progressive forms, made with compound forms of be, are described below.

The basic present and past tenses of the verb are called simple present (present simple) and simple past (past simple), to distinguish them from progressive or other compound forms. Thus the simple present of the above verb is write or writes, and the simple past (also called preterite) is wrote.

Perfect

The perfect aspect is expressed with a form of the auxiliary have together with the past participle of the verb. Thus the present perfect is have written or has written, and the past perfect (pluperfect) is had written. The perfect can combine with the progressive aspect (see above) to produce the present perfect progressive (continuous) have/has been writing and the past perfect progressive (continuous) had been writing.

There is a perfect infinitive (to) have written and a perfect progressive infinitive (to) have been writing, and corresponding present participle/gerund forms having written and having been writing. A perfect subjunctive (have written) is also sometimes used. Future and conditional perfect forms are given below.