The services provided by airlines can be divided into three distinct categories: scheduled services, charter services and _________.
A.“frequent” programs
B.air taxi services
C.executive aircraft
D.extra free travel
正确答案是B
The services provided by airlines can be divided into three distinct categories: scheduled services, charter services and _________.
A.“frequent” programs
B.air taxi services
C.executive aircraft
D.extra free travel
正确答案是B