-----------------------------------
若い頃， 若いころ， わかいころ
1. one's youth, early life, one's early days, one's early years
tbd
-----------------------------------
違いない， 違い無い， ちがいない
1. sure, no mistaking it, for certain, without doubt
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
に
1. at (place, time), in, on, during
2. to (direction, state), toward, into
3. for (purpose)
4. because of (reason), for, with
5. by, from
6. as (i.e. in the role of)
7. per, in, for, a (e.g. "once a month")
8. and, in addition to
9. if, although
tbd
