If you commission in to the Air Force as a non-rated officer (not a pilot, navigator, air battle manager) you'll be required to serve 4 years active duty. Pilots are required to serve 10 years. Basically it would be 8 years active (2ish years for flight school, 6 years actually flying) then 2 years inactive........
Stumbling block. For other uses, see Stumbling block (disambiguation). A stumbling block or scandal in the Bible is a metaphor for a behavior or attitude that leads another to sin.
chemical group, radical, group - (chemistry) two or more atoms bound together as a single unit and forming part of a molecule. molecule - (physics and chemistry) the simplest structural unit of an element or compound. ashlar - a rectangular block of hewn stone used for building purposes. breeze block, cinder block, clinker block - a light concrete building block made with cinder aggregate; cinder blocks are called breeze blocks in Britain.