Declining revenues resulting from a decrease in business travel, a source of income without which most commercial airlines could not survive, are
going to force many commercial airlines to increase prices and decrease services in the coming months.
B) a source of income without which most commercial airlines could not survive, is
C) and most commercial airlines use it as a source of income to survive with, are
D) which is a source of income which is needed by most commercial airlines who could not survive without it, are
E) which most commercial airlines use as a source of income without which they are unable to survive, is
The sky is the limit
800 is the limit