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こないだ， 此間
1. the other day, lately, recently
前几天，最近，近来
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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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なくす， 無くす， 失くす
1. to lose (something)
2. to get rid of, to eliminate, to remove, to eradicate, to abolish
丢失；摆脱，消除