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沈む， しずむ
1. to sink, to go under, to submerge
2. to go down (e.g. sun), to set, to descend
3. to feel depressed, to become subdued, to become somber
下沉，沉没，淹没；感到沮丧，变得低落，变得阴郁
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
の
1. indicates possessive
2. nominalizes verbs and adjectives
3. substitutes for "ga" in subordinate phrases
4. (at sentence-end, falling tone) indicates a confident conclusion
5. (at sentence-end) indicates emotional emphasis
6. (at sentence-end, risi...
句尾起强调作用；助词，表示所有关系
