Input: Article: Though almost any variety of acoustic mandolin might be adequate for Irish traditional music, virtually all Irish players prefer flat-backed instruments with oval sound holes to the Italian-style bowl-back mandolins or the carved-top mandolins with f-holes favoured by bluegrass mandolinists. The former are often too soft-toned to hold their own in a session (as well as having a tendency to not stay in place on the player's lap), whilst the latter tend to sound harsh and overbearing to the traditional ear. The f-hole mandolin, however, does come into its own in a traditional session, where its brighter tone cuts through the sonic clutter of a pub. Greatly preferred for formal performance and recording are flat-topped "Irish-style" mandolins (reminiscent of the WWI-era Martin Army-Navy mandolin) and carved (arch) top mandolins with oval soundholes, such as the Gibson A-style of the 1920s.

Now answer this question: Which type mandolin had a tendency not to stay in the player's lap?

Output: the carved-top mandolins with f-holes

Input: Article: The emergence of resistance of bacteria to antibiotics is a common phenomenon. Emergence of resistance often reflects evolutionary processes that take place during antibiotic therapy. The antibiotic treatment may select for bacterial strains with physiologically or genetically enhanced capacity to survive high doses of antibiotics. Under certain conditions, it may result in preferential growth of resistant bacteria, while growth of susceptible bacteria is inhibited by the drug. For example, antibacterial selection for strains having previously acquired antibacterial-resistance genes was demonstrated in 1943 by the LuriaDelbruck experiment. Antibiotics such as penicillin and erythromycin, which used to have a high efficacy against many bacterial species and strains, have become less effective, due to the increased resistance of many bacterial strains.

Now answer this question: When was antibacterial-resistance demonstrated?

Output: 1943

Input: Article: London is a major international air transport hub with the busiest city airspace in the world. Eight airports use the word London in their name, but most traffic passes through six of these. London Heathrow Airport, in Hillingdon, West London, is the busiest airport in the world for international traffic, and is the major hub of the nation's flag carrier, British Airways. In March 2008 its fifth terminal was opened. There were plans for a third runway and a sixth terminal; however, these were cancelled by the Coalition Government on 12 May 2010.

Now answer this question: How many airports are affiliated with London and incorporate the word London in their names?

Output:
Eight