The workers busily when the boss came to look for something she in the office. A had worke

问题补充：

The workers busily when the boss came to look for something she in the office.

A had worked, had leftB were working ; had left C working ; had left D had worked; left

答案：

解析：前一空表示当时正在进行的动作，所以用过去进行时，第二空用过去进行时表示这动作在came之前。