【题目】Holiday is coming. Students are busy _______ their things in the suitcase.
A.pack upB.packing up
C.packing offD.pack into
在线课程【答案】B
【解析】
考查动词短语辨析和固定用法。句意：假期即将来临。学生们正忙着把东西装进手提箱。A. pack up把…打包；B. packing up把…打包；C. packing off打发走（某人）；D. pack into挤进…里。be busy doing忙着做某事，该用法是固定用法，故选B。