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協力， きょうりょく
1. cooperation, collaboration, help, support
合作、协作、帮助、支持
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なくてはならない， 無くてはならない
1. cannot do without something, indispensable, absolutely necessary
2. have to do
必不可少，绝对必要；必须
が
1. indicates the subject of a sentence
2. indicates possession
3. but, however, (and) yet, though, although, while
4. and
5. used after an introductory remark or explanation
6. regardless of ..., whether ... (or not), no matter ...
7. indicates a des...
tbd
