11.  They are both undertaking critical jobs.

12.  Army officials will start negotiations with the companies to determine whether the proposal has the potential to benefit the arsenal and maintain critical job skills, Abney said.

13.  Officers, rather than enlisted personnel, hold the most critical jobs at NORAD and Peterson.

14.  Two spacewalking astronauts floated outside early Tuesday and finished a critical wiring job on the international space station.

15.  Two spacewalking astronauts floated outside early Tuesday to finish a critical wiring job on the international space station.