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C100 · 普通句（141 课）
Convincing evidence to support this theory is hard to obtain
Course 100
(普)Convincing evidence to support this theory is hard to obtain.
1 句 · 父母与孩子分角色配音
旁白 neutral
Convincing evidence to support this theory is hard to obtain
要获得支持这一理论的有力证据很困难
