Input: Read this: In grading lumber and structural timber, knots are classified according to their form, size, soundness, and the firmness with which they are held in place. This firmness is affected by, among other factors, the length of time for which the branch was dead while the attaching stem continued to grow.
Question: What property of knots does the amount of time a branch stayed on a tree while the stem kept growing affect?

Output: firmness


Input: Read this: The first Grand Lodge, the Grand Lodge of London and Westminster (later called the Grand Lodge of England (GLE)), was founded on 24 June 1717, when four existing London Lodges met for a joint dinner. Many English Lodges joined the new regulatory body, which itself entered a period of self-publicity and expansion. However, many Lodges could not endorse changes which some Lodges of the GLE made to the ritual (they came to be known as the Moderns), and a few of these formed a rival Grand Lodge on 17 July 1751, which they called the "Antient Grand Lodge of England." These two Grand Lodges vied for supremacy until the Moderns promised to return to the ancient ritual. They united on 27 December 1813 to form the United Grand Lodge of England (UGLE).
Question: Which lodges refused to join the new regulatory body?

Output: unanswerable


Input: Read this: The word asphalt is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning "asphalt/bitumen/pitch", which perhaps derives from ἀ-, "without" and σφάλλω (sfallō), "make fall". Note that in French, the term asphalte is used for naturally occurring bitumen-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the "asphaltic concrete" used to pave roads. It is a significant fact that the first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall. From the Greek, the word passed into late Latin, and thence into French (asphalte) and English ("asphaltum" and "asphalt").
Question: According to who was bitumen brought to Greece to build a giant wall?

Output: unanswerable


Input: Read this: Phil Skinner played a key role in 20th century development of the mandolin movement in Australia, and was awarded an MBE in 1979 for services to music and the community. He was born Harry Skinner in Sydney in 1903 and started learning music at age 10 when his uncle tutored him on the banjo. Skinner began teaching part-time at age 18, until the Great Depression forced him to begin teaching full-time and learn a broader range of instruments. Skinner founded the Sydney Mandolin Orchestra, the oldest surviving mandolin orchestra in Australia.
Question:  When did the African mandolin movement begin?

Output:
unanswerable