必要, 必用, ひつよう
NA-adjective, 必用 can imply has to be used rather than is just needed
1. necessary, needed, essential, indispensable
2. necessity, need, requirement
歯医者に行く必要はない。
が
Particle
1. indicates sentence subject (occasionally object)
2. indicates possessive (esp. in literary expressions)
Conjunction
3. but, however, still, and
after the volitional form of a verb
4. regardless of, whether (or not)
ある, 有る, 在る
Godan verb, Intransitive, See 居る・いる・1, Usually in kana, usu. of inanimate objects
1. to be, to exist, to live
2. to have
3. to be located
4. to be equipped with
5. to happen, to come about
悪いけどほかに用事があるの。
ある, 或る, 或
Pre-noun adjectival (rentaishi), Usually in kana
a certain ..., some ...
ある学生に会うところです。