Imperfective
In Japanese, the basic verb form is an imperfective aspect. It is broadly equivalent to the present and future tenses of English, and is sometimes called the "non-past tense". The imperfective form of a verb is the same as its dictionary form—it is used as the headword, or lemma—and no conjugation needs to be done. For example, using the verb する ("do"):
- (私は)買い物する (watashi wa) kaimono suru: "(I) shop", or "(I) will shop". (Japanese pronouns are usually omitted when it is clear about whom the speaker is talking.)
- (私は)明日勉強する (watashi wa) ashita benkyō suru: "Tomorrow, (I) will study".
In most cases, the base form of the imperfective aspect cannot be used to make a progressive statement, such as in the English sentence "I am shopping". Rather, it can only be used to express habit or other actions that are expected to continue into the future, such as in "I shop". To convey the former, the te form with iru must be used.
Read more about this topic: Japanese Verb Conjugation