Input: Read this: Many birds show plumage patterns in ultraviolet that are invisible to the human eye; some birds whose sexes appear similar to the naked eye are distinguished by the presence of ultraviolet reflective patches on their feathers. Male blue tits have an ultraviolet reflective crown patch which is displayed in courtship by posturing and raising of their nape feathers. Ultraviolet light is also used in foraging—kestrels have been shown to search for prey by detecting the UV reflective urine trail marks left on the ground by rodents. The eyelids of a bird are not used in blinking. Instead the eye is lubricated by the nictitating membrane, a third eyelid that moves horizontally. The nictitating membrane also covers the eye and acts as a contact lens in many aquatic birds. The bird retina has a fan shaped blood supply system called the pecten. Most birds cannot move their eyes, although there are exceptions, such as the great cormorant. Birds with eyes on the sides of their heads have a wide visual field, while birds with eyes on the front of their heads, such as owls, have binocular vision and can estimate the depth of field. The avian ear lacks external pinnae but is covered by feathers, although in some birds, such as the Asio, Bubo and Otus owls, these feathers form tufts which resemble ears. The inner ear has a cochlea, but it is not spiral as in mammals.
Question: What covers the eye and acts as a contact lens in many aquatic birds?

Output: nictitating membrane


Input: Read this: These symmetries are represented by functions. Each of these functions sends a point in the square to the corresponding point under the symmetry. For example, r1 sends a point to its rotation 90° clockwise around the square's center, and fh sends a point to its reflection across the square's vertical middle line. Composing two of these symmetry functions gives another symmetry function. These symmetries determine a group called the dihedral group of degree 4 and denoted D4. The underlying set of the group is the above set of symmetry functions, and the group operation is function composition. Two symmetries are combined by composing them as functions, that is, applying the first one to the square, and the second one to the result of the first application. The result of performing first a and then b is written symbolically from right to left as
Question:  What gives another symmetry function?

Output: Composing two of these symmetry functions


Input: Read this: In empirical therapy, a patient has proven or suspected infection, but the responsible microorganism is not yet unidentified. While the microorgainsim is being identified the doctor will usually administer the best choice of antibiotic that will be most active against the likely cause of infection usually a broad spectrum antibiotic. Empirical therapy is usually initiated before the doctor knows the exact identification of microorgansim causing the infection as the identification process make take several days in the laboratory.
Question: How long does the infection process take?

Output: unanswerable


Input: Read this: Everton hold the record for the most seasons in England's top tier (Division One/Premier League), at 111 seasons out of 114 as of 2014–15 (the club played in Division 2 in 1930–31 and from 1951–54). They are one of seven teams to have played all 22 seasons of the Premier League since its inception in August 1992 – the others being Arsenal, Aston Villa, Chelsea, Liverpool, Manchester United, and Tottenham Hotspur. Everton against Aston Villa is the most played fixture in England's top flight, as of the 2012–13 season the two founder members of the Football League have played a record 196 league games.
Question: How many games has Everton played against Aston Villa?

Output:
196