Question

2. She must have been terribly tired last night. She        without a break for over ten hours (work)

她昨晚一定非常累。她已连续工作了十个多小时。

Answer 1

2. had been working前文是对过去某情况的推测，显然work之动作发生在疲劳之前，且一直持续，因此用过去完成进行时态。