Japanese nouns have neither number nor gender. Thus hon may mean "book" or "books". It is possible to explicitly indicate more than one, either by providing a quantity (often with a counter word) or by adding a suffix (which is rare). Words for people are usually understood as singular. Thus Tanaka-san usually means Mr./Ms. Tanaka. Words that refer to people and animals can be made to indicate a group of individuals through the addition of a collective suffix (a noun suffix that indicates a group), such as -tachi. Though some words, like hitobito "people", always refer to more than one, Japanese nouns without such additions are neither singular nor plural. Hito could mean "person" or "persons", ki could be "tree" or "trees" without any implied preference for singular or plural.
Verbs are conjugated to show tenses, of which there are two: past and present, or non-past, which is used for the present and the future. For verbs that represent an ongoing process, the -te iru form indicates a continuous (or progressive) tense. For others that represent a change of state, the -te iru form indicates a perfect tense. For example, kite iru means "He has come (and is still here)", but tabete iru means "He is eating".
Questions (both with an interrogative pronoun and yes/no questions) have the same structure as affirmative sentences, but with intonation rising at the end. In the formal register, the question particle -ka is added. For example, Ii desu "It is OK" becomes Ii desu-ka "Is it OK?". In a more informal tone sometimes the particle -no is added instead to show a personal interest of the speaker: Dōshite konai-no? "Why aren't (you) coming?". Some simple queries are formed simply by mentioning the topic with an interrogative intonation to call for the hearer's attention: Kore-wa? "(What about) this?"; Namae-wa? "(What's your) name?".
Negatives are formed by inflecting the verb. For example, Pan-o taberu "I will eat bread" or "I eat bread" becomes Pan-o tabenai "I will not eat bread" or "I do not eat bread".
The so-called -te verb form is used for a variety of purposes: either progressive or perfect aspect (see above); combining verbs in a temporal sequence (Asagohan-o tabete sugu dekakeru "I'll eat breakfast and leave at once"), simple commands, conditional statements and permissions (Dekakete-mo ii? "May I go out?"), etc.
The word da (plain), desu (polite) is the copula verb. It corresponds approximately to the English be, but often takes on other roles. Two additional common verbs are used to indicate existence ("there is") or, in some contexts, property: aru (negative nai) and iru (negative inai), for inanimate and animate things, respectively. For example, Neko ga iru "There's a cat", Ii kangae-ga nai " haven't got a good idea".
The verb "to do" (suru, polite form shimasu) is often used to make verbs from nouns (ai suru "to love", benkyō suru "to study", etc.). Japanese also has a huge number of compound verbs to express concepts that are described in English using a verb and a preposition (e.g. tobidasu "to fly out, to flee," from tobu "to fly, to jump" + dasu "to put out, to emit").
There are three types of adjective (see also Japanese adjectives):
1. keiyōshi, or i adjectives, which have a conjugating ending i (such as atsui, "to be hot") which can become past (atsukatta - "it was hot"), or negative (atsuku nai - "it is not hot"). Note that nai is also an i adjective, which can become past (atsuku nakatta - it was not hot).
atsui hi "a hot day".
2. keiyōdōshi, or na adjectives, which are followed by a form of the copula, usually na. For example hen (strange)
hen na hito "a strange person".
3. rentaishi, also called true adjectives, such as onaji "the same"
onaji hi "the same day".
