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注意深く， ちゅういぶかく
1. attentively, cautiously, carefully, watchfully, with caution
小心地，谨慎地，留心地
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なければならない， なければなりません， なければいけない
1. have to do, must, should, ought to
必须，应该
本， ほん
1. book, volume, script
2. this, present, current, ... in question, ... at issue
3. main, head, principal
4. real, genuine, regular, proper
5. counter for long, cylindrical things, counter for films, TV shows, etc., counter for goals, home runs, etc....
书
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
