Information:  - The Douglas Aircraft Company was an American aerospace manufacturer based in Southern California. It was founded in 1921 by Donald Wills Douglas, Sr. and later merged with McDonnell Aircraft in 1967 to form McDonnell Douglas. Douglas Aircraft Company largely operated as a division of McDonnell Douglas (MD) after the merger. MD later merged with Boeing in 1997.  - Air-to-ground weaponry is aircraft ordnance used by combat aircraft to attack ground targets. The weapons include bombs, machine guns, autocannon, air-to-surface missiles, rockets, air-launched cruise missiles and grenade launchers.  - The Douglas B - 23 Dragon is a twin - engined bomber developed by the Douglas Aircraft Company as a successor to ( and a refinement of ) the B - 18 Bolo .  - The Boeing Company is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, and satellites worldwide. The company also provides leasing and product support services. Boeing is among the largest global aircraft manufacturers; it is the second-largest defense contractor in the world based on 2015 revenue, and is the largest exporter in the United States by dollar value. Boeing stock is a component of the Dow Jones Industrial Average.  - An aerospace manufacturer is a company or individual involved in the various aspects of designing, building, testing, selling, and maintaining aircraft, aircraft parts, missiles, rockets, and/or spacecraft. Aerospace is a high technology industry.  - Donald Wills Douglas, Sr. (6 April 1892  1 February 1981) was an American aircraft industrialist and engineer.  - Southern California, often abbreviated as SoCal, is a geographic and cultural region that generally comprises California's 10 southernmost counties. The region is traditionally described as eight counties, based on demographics and economic ties: Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, and Ventura. The more extensive 10-county definition, which includes Kern and San Luis Obispo counties, is also used based on historical political divisions. Southern California is a major economic center for the state of California and the United States.  - A bomber is a combat aircraft designed to attack ground and sea targets by dropping air-to-ground weaponry, firing torpedoes or deploying air-launched cruise missiles.  - The McDonnell Aircraft Corporation was an American aerospace manufacturer based in St. Louis, Missouri. The company was founded on July 6, 1939 by James Smith McDonnell, and was best known for its military fighters, including the F-4 Phantom II, and manned spacecraft including the Mercury capsule and Gemini capsule. McDonnell Aircraft later merged with the Douglas Aircraft Company to form McDonnell Douglas in 1967.  - McDonnell Douglas was a major American aerospace manufacturing corporation and defense contractor formed by the merger of McDonnell Aircraft and the Douglas Aircraft Company in 1967. Between then and its own merger with Boeing in 1997, it produced a number of well-known commercial and military aircraft such as the DC-10 airliner and F-15 Eagle air-superiority fighter.    Given the information, choose the subject and object entities that have the relation of 'subclass of'.
Ans: douglas b-23 dragon , military aircraft

Information:  - Eleanor Frances (Butler) Cameron (19121996) was a children's author and critic. She published 20 books in her lifetime, including "The Wonderful Flight to the Mushroom Planet" (1954) and its sequels, a collection of critical essays called "The Green and Burning Tree" (1969), and "The Court of the Stone Children" (1973), which won the U.S. National Book Award in category Children's Books  - Stowaway to the Mushroom Planet is the second in the series of Mushroom Planet books by Eleanor Cameron , and was published in 1956 , two years after the original . This children 's book is set in a beach community in California , as well as on a tiny , habitable moon -- `` Basidium '' -- in an invisible orbit 50,000 miles from Earth . The `` Mushroom Planet , '' visited by the protagonists David and Chuck , is covered in various types of mushrooms and is populated by little green people .  - The Wonderful Flight to the Mushroom Planet is a children's science fiction novel written by Eleanor Cameron, illustrated by Robert Henneberger, and published by Little, Brown in 1954. It is set in Pacific Grove, California, and on Basidium, a tiny habitable moon of Earth, invisible from the planet in its orbit 50,000 miles away. The "Mushroom Planet", visited by the protagonists David Topman and Chuck Masterson, is covered in various types of mushrooms and is populated by little green people who are in a state of distress.    Given the information, choose the subject and object entities that have the relation of 'follows'.
Ans: stowaway to the mushroom planet , the wonderful flight to the mushroom planet

Information:  - The Headford Ambush took place on 21 March 1921 , during the Irish War of Independence . The Second Kerry Brigade ( South Kerry ) of the Irish Republican Army ( IRA ) ambushed a train carrying British troops at Headford Junction railway station ( near Killarney , County Kerry ) . A total of at least 16 people died in the incident -- 10 British soldiers , 2 IRA volunteers and 4 civilians ( including an informer killed after the ambush ) .  - The Irish Republic (or ) was a revolutionary state that declared its independence from Britain in January 1919. In theory the Republic covered the whole island of Ireland, but by 1920 its functional control was limited to only 21 of Ireland's 32 counties, and British state forces maintained presence across much of the north-east, as well as Cork, Dublin and other major towns.  - The Irish War of Independence or Anglo-Irish War or the Tan War was a guerrilla war fought from 1919 to 1921 between the Irish Republican Army (IRA, the army of the Irish Republic) and the British security forces in Ireland. It was an escalation of the Irish revolutionary period into armed conflict.    Given the information, choose the subject and object entities that have the relation of 'instance of'.
Ans: headford ambush , conflict