她忙于备课
She is busy preparing lessons
以上为机器翻译结果，长、整句建议使用 人工翻译 。
她忙于备课。
She was busy preparing lessons.
youdao
新的学期刚刚开始。她现在一定是忙于备课。
The new term has just started. She must be very busy preparing her lessons.
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