She is very shy, so her Japanese didn't improve very rapidly, but she was a very industrious learner.

industrious 是由名词 industry（工业、勤奋）加上形容词后缀 -ous 构成的形容词，意思是"勤奋的、勤劳的"。 learner 是由动词 learn（学习）加上名词后缀 -er 构成的名词，表示"学习者、学生"，后缀 -er 通常表示"从事某种活动的人"。 industrious learner 指"勤奋的学习者"。