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.
It's kinda like a database. A blockchain is a ledger of records arranged in data batches called blocks that use cryptographic validation to link themselves together. Put simply, each block references and identifies the previous block by a hashing function, forming an unbroken chain, hence the name. Further Reading Bitcoin firm bags first electronic money licence in the UK