We were told not to touch the equipment in the laboratory unless ________. A. allowed to do B. all
问题描述：
We were told not to touch the equipment in the laboratory unless ________. A. allowed to do B. all
We were told not to touch the equipment in the laboratory unless ________.
A. allowed to do B. allowing to do C. allowed to D. allowing to
答
省略句,其实后面是unless we were allowed to do it（直到我们被允许做某事）,后面的do it省略,就是动词不定式的省略形式,所以选C