The second decline was not as complete as the first. Thousands of people had learned to play the instrument. Even as the second wave of mandolin popularity declined in the early 20th century, new versions of the mandolin began to be used in new forms of music. Luthiers created the resonator mandolin, the flatback mandolin, the carved-top or arched-top mandolin, the mandolin-banjo and the electric mandolin. Musicians began playing it in Celtic, Bluegrass, Jazz and Rock-n-Roll styles — and Classical too.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"):  What is the third type of new mandolins the Luthiers created?
Ah, so.. unanswerable

A person may display either relative weakness or relative strength in terms of both exploration and commitments. When assigned categories, four possible permutations result: identity diffusion, identity foreclosure, identity moratorium, and identity achievement. Diffusion is when a person lacks both exploration in life and interest in committing even to those unchosen roles that he or she occupies. Foreclosure is when a person has not chosen extensively in the past, but seems willing to commit to some relevant values, goals, or roles in the future. Moratorium is when a person displays a kind of flightiness, ready to make choices but unable to commit to them. Finally, achievement is when a person makes identity choices and commits to them.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What is a permutation when a person is not ready to make a commitment?
Ah, so.. unanswerable

Bitumen was used in early photographic technology. In 1826 or 1827, it was used by French scientist Joseph Nicéphore Niépce to make the oldest surviving photograph from nature. The bitumen was thinly coated onto a pewter plate which was then exposed in a camera. Exposure to light hardened the bitumen and made it insoluble, so that when it was subsequently rinsed with a solvent only the sufficiently light-struck areas remained. Many hours of exposure in the camera were required, making bitumen impractical for ordinary photography, but from the 1850s to the 1920s it was in common use as a photoresist in the production of printing plates for various photomechanical printing processes.[not in citation given]
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What feature of bitumen use in photography made it impractical?
Ah, so..
hours of exposure