It was often difficult to know where his allegiances lay.
It was often difficult with them to tell where teasing gave way to real tension.
In violent attacks it was often difficult, and sometimes meaningless, to distinguish perpetrators from victims.
As such, they said, it was often difficult to explain to their pupils the struggles they had experienced as youngsters.
Energy Department managers told the auditors it was often difficult to balance their chief mission goals with energy conservation measures, the report said.
In former days it was often difficult to distinguish between one article and the next, because distinctive headings or inset titles or the use of boldface was rare.
The secular mystery clubs continued throughout Greek and Roman history, and it was often difficult to distinguish them from religious associations.
Ms. Jefferson of the F.D.A. said it was often difficult when a drug is approved, and even afterward, to pinpoint how it works.
In 1980, after "Above London" was published, Mr. Cameron told The New York Times that it was often difficult to get permission to fly over a city.
But labor leaders said it was often difficult for these Americans to join a union because many employers fought organizing efforts.
As the conveyor belt ferrying morsels from the counter-culture into the mainstream speeded up, it was often difficult to tell who owned what.
