Given the following passage "In February 1918, he was appointed Officer in Charge of Boys at the Royal Naval Air Service's training establishment at Cranwell. With the establishment of the Royal Air Force two months later and the transfer of Cranwell from Navy to Air Force control, he transferred from the Royal Navy to the Royal Air Force. He was appointed Officer Commanding Number 4 Squadron of the Boys' Wing at Cranwell until August 1918, before reporting to the RAF's Cadet School at St Leonards-on-Sea where he completed a fortnight's training and took command of a squadron on the Cadet Wing. He was the first member of the royal family to be certified as a fully qualified pilot. During the closing weeks of the war, he served on the staff of the RAF's Independent Air Force at its headquarters in Nancy, France. Following the disbanding of the Independent Air Force in November 1918, he remained on the Continent for two months as a staff officer with the Royal Air Force until posted back to Britain. He accompanied the Belgian monarch King Albert on his triumphal reentry into Brussels on 22 November. Prince Albert qualified as an RAF pilot on 31 July 1919 and gained a promotion to squadron leader on the following day.", answer the following question. Note that the answer is present within the text. Question: What happened after June 1919?
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Answer: Prince Albert qualified as an RAF pilot on 31 July 1919 and gained a promotion to squadron leader on the following day

Given the following passage "The humoral (antibody) response is defined as the interaction between antibodies and antigens. Antibodies are specific proteins released from a certain class of immune cells known as B lymphocytes, while antigens are defined as anything that elicits the generation of antibodies ("anti"body "gen"erators). Immunology rests on an understanding of the properties of these two biological entities and the cellular response to both.", answer the following question. Note that the answer is present within the text. Question: Antigens illicit the release of what in the body?
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Answer: antibodies

Given the following passage "Ion gauges are used in ultrahigh vacuum. They come in two types: hot cathode and cold cathode. In the hot cathode version an electrically heated filament produces an electron beam. The electrons travel through the gauge and ionize gas molecules around them. The resulting ions are collected at a negative electrode. The current depends on the number of ions, which depends on the pressure in the gauge. Hot cathode gauges are accurate from 103 torr to 1010 torr. The principle behind cold cathode version is the same, except that electrons are produced in a discharge created by a high voltage electrical discharge. Cold cathode gauges are accurate from 102 torr to 109 torr. Ionization gauge calibration is very sensitive to construction geometry, chemical composition of gases being measured, corrosion and surface deposits. Their calibration can be invalidated by activation at atmospheric pressure or low vacuum. The composition of gases at high vacuums will usually be unpredictable, so a mass spectrometer must be used in conjunction with the ionization gauge for accurate measurement.", answer the following question. Note that the answer is present within the text. Question: What can be used to make sure the readouts from an ion gauge are as close to correct as possible?
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Answer:
mass spectrometer