Article: The essence of air defence is to detect hostile aircraft and destroy them. The critical issue is to hit a target moving in three-dimensional space; an attack must not only match these three coordinates, but must do so at the time the target is at that position. This means that projectiles either have to be guided to hit the target, or aimed at the predicted position of the target at the time the projectile reaches it, taking into account speed and direction of both the target and the projectile.

Question: What is the first purpose of air defence?
Ans: detect hostile aircraft

Article: In 1986, eight years before the launch of Turner Classic Movies, Ted Turner acquired the Metro-Goldwyn-Mayer film studio for $1.5 billion. Concerns over Turner Entertainment's corporate debt load resulted in Turner selling the studio that October back to Kirk Kerkorian, from whom Turner had purchased the studio less than a year before. As part of the deal, Turner Entertainment retained ownership of MGM's library of films released up to May 9, 1986. Turner Broadcasting System was split into two companies; Turner Broadcasting System and Metro-Goldwyn-Mayer and reincorporated as MGM/UA Communications Co.

Question: How much did Ted Turner pay for Metro-Goldwyn Mayer?
Ans: $1.5 billion

Article: In Western Catalan, unstressed vowels reduce to five: /e / > [e]; /o / > [o]; /a u i/ remain distinct. This reduction pattern, inherited from Proto-Romance, is also found in Italian and Portuguese. Some Western dialects present further reduction or vowel harmony in some cases.

Question: What do other Western dialects sometimes offer?
Ans: further reduction

Article: Although provision is made in Title 10 of the United States Code for the Secretary of the Air Force to appoint warrant officers, the Air Force does not currently use warrant officer grades, and is the only one of the U.S. Armed Services not to do so. The Air Force inherited warrant officer ranks from the Army at its inception in 1947, but their place in the Air Force structure was never made clear.[citation needed] When the Congress authorized the creation of two new senior enlisted ranks in 1958, Air Force officials privately concluded that these two new "super grades" could fill all Air Force needs then performed at the warrant officer level, although this was not publicly acknowledged until years later.[citation needed] The Air Force stopped appointing warrant officers in 1959, the same year the first promotions were made to the new top enlisted grade, Chief Master Sergeant. Most of the existing Air Force warrant officers entered the commissioned officer ranks during the 1960s, but small numbers continued to exist in the warrant officer grades for the next 21 years.

Question: When did the USAF stop appointing warrant officers?
Ans:
1959