Article: Starting in 1910, the army began acquiring fixed-wing aircraft. In 1910, Mexico was having a civil war, peasant rebels fighting government soldiers. The army was deployed to American towns near the border to ensure safety to lives and property. In 1916, Pancho Villa, a major rebel leader, attacked Columbus, New Mexico, prompting a U.S. intervention in Mexico until 7 February 1917. They fought the rebels and the Mexican federal troops until 1918. The United States joined World War I in 1917 on the side of Britain, France, Russia, Italy and other allies. U.S. troops were sent to the Western Front and were involved in the last offensives that ended the war. With the armistice in November 1918, the army once again decreased its forces.

Question: What year did the U.S. join World War I?
Ans: 1917

Article: The onset of symptoms in myocardial infarction (MI) is usually gradual, over several minutes, and rarely instantaneous. Chest pain is the most common symptom of acute MI and is often described as a sensation of tightness, pressure, or squeezing. Chest pain due to ischemia (a lack of blood and hence oxygen supply) of the heart muscle is termed angina pectoris. Pain radiates most often to the left arm, but may also radiate to the lower jaw, neck, right arm, back, and upper abdomen, where it may mimic heartburn. Levine's sign, in which a person localizes the chest pain by clenching their fists over their sternum, has classically been thought to be predictive of cardiac chest pain, although a prospective observational study showed it had a poor positive predictive value.

Question: What does ischemia refer too?
Ans: a lack of blood

Article: The inflection of determinatives is complex, specially because of the high number of elisions, but is similar to the neighboring languages. Catalan has more contractions of preposition + article than Spanish, like dels ("of + the [plural]"), but not as many as Italian (which has sul, col, nel, etc.).

Question: What type of word is added to the contraction of the preposition?
Ans: article

Article: The first legislation providing federal authority for regulating pesticides was enacted in 1910; however, decades later during the 1940s manufacturers began to produce large amounts of synthetic pesticides and their use became widespread. Some sources consider the 1940s and 1950s to have been the start of the "pesticide era." Although the U.S. Environmental Protection Agency was established in 1970 and amendments to the pesticide law in 1972, pesticide use has increased 50-fold since 1950 and 2.3 million tonnes (2.5 million short tons) of industrial pesticides are now[when?] used each year. Seventy-five percent of all pesticides in the world are used in developed countries, but use in developing countries is increasing. A study of USA pesticide use trends through 1997 was published in 2003 by the National Science Foundation's Center for Integrated Pest Management.

Question: What might someone knowledgable about the history of pesticides call ther period of the 1940s and 1950s?
Ans:
pesticide era