Assertion: air hijacking | /r/HasAspect | several distinct periods
Facets:
value: to 1967
type: TEMPORAL
value: to 1980
type: TEMPORAL
value: to the present
type: TEMPORAL
Source sentences:
text: From the point of view of Americans, air hijacking can be divided into several distinct periods: 1931 to 1957, 1958 to 1967, 1968 to, roughly, 1980, 1980 to 2001, and 2001 to the present.