It is difficult to tell exactly ____ the saying began, but it is probable that it was in the theater or movie industry.

He, out of breath, _____ himself along the street. Perhaps he was badly ill. [ ]

r,in recent years, ___Three Gorges have come to be appreciated more for theirnatural beauty as ___ wonder of Nature

___ gas leaks and similar accidentsshould occur, some responsible persons should regularly inspect all thelaboratories.

The TV drama _________ the north of China during the anti-Japanese war. [ ]