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必要， 必用， ひつよう
1. necessary, needed, essential, indispensable
2. necessity, need, requirement
必要的，必需的，必不可少的，不可缺少的；必要性，需要，要求
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を
1. indicates direct object of action
2. indicates subject of causative expression
3. indicates an area traversed
4. indicates time (period) over which action takes place
5. indicates point of departure or separation of action
6. indicates object of d...
表示动作的直接对象；表示经过的场所；表示离开或分开的点
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取る， とる
1. to take, to pick up, to grab, to catch
2. to pass, to hand, to give
3. to get, to obtain, to acquire, to win, to receive, to earn, to take (e.g. a vacation)
4. to adopt (a method, proposal, etc.), to take (a measure, attitude, etc.), to choose
5. ...
采、拿、拾、抓取、抓住；传递、交付、给予；拿，得到
は
1. indicates sentence topic
2. indicates contrast with another option (stated or unstated)
3. adds emphasis
指示句子的主题；表示与另一选项（无论是否明确提及）形成对比；表示强调
