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本題， ほんだい
1. main topic, main subject, main issue, main question
2. this subject
tbd
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
から
1. from (e.g. time, place, numerical quantity), since
2. from (originator), by
3. because, since
4. out of (constituent, part)
5. through (e.g. window, vestibule)
6. after, since
7. expresses sympathy or warning
从，自……；因为；被，用于……
