Question: David Monroe Shoup (30 December 1904 - 13 January 1983) was a decorated general of the United States Marine Corps who was awarded the Medal of Honor in World War II, became the 22nd Commandant of the Marine Corps, and, after retiring, became one of the most prominent critics of the Vietnam War. Born in Indiana to an impoverished family, Shoup joined the military for financial reasons. Rising through the ranks in the interwar era, he was twice deployed to China during the Chinese Civil War. He served in Iceland at the beginning of U.S. involvement in World War II, and as a staff officer during the Pacific War.

David Monroe Shoup was born on 30 December 1904 in Battle Ground, Indiana. His family lived on a farm in Ash Grove, but moved to Covington to live on a new farm in 1916. At age 12 he was enrolled in Covington High School, a competitive high school with an advanced curriculum. Shoup was an excellent student, maintaining high marks in French, English, physics, and history. Additionally, he was involved in several extracurricular activities, including basketball, and was class president in his senior year. He graduated in 1921. He later affectionately referred to his impoverished upbringing as that of an "Indiana plowboy." Regarded by friends as very sociable, he met Zola De Haven in his freshman year and later said he had been instantly attracted to her. They were both very competitive in academics and athletics, and the two dated throughout high school; they were married in 1931. After high school, Shoup attended DePauw University where he was one of 100 awarded the Edward Rector Scholarship, giving him full tuition. Majoring in mathematics, he joined the Delta Upsilon fraternity and maintained high marks, narrowly failing the selection criteria for Phi Beta Kappa Society. He was on the track and field and rifle teams, and also competed in the wrestling and football teams. He won the Indiana and Kentucky Amateur Athletic Union marathon in 1925. He waited tables, washed dishes and worked in a cement factory to help pay his expenses. Lack of funds compelled him to take a year off after his junior year to teach school, and his expenses were further strained when he contracted a severe case of pneumonia and incurred hospital bills. He opted to enroll in the Reserve Officers Training Corps (ROTC) to offset his living expenses, and later recalled that this was the only reason he joined the military. He graduated from DePauw in 1926. From an early age, Shoup was molded by the progressive ideas of Indiana politicians, sympathizing with rural progressives fighting against the interests of big businesses. He developed an anti-imperialist attitude, and his skepticism about American foreign policy, influenced by his small-town background, made him an outspoken opponent of the unnecessary use of military force. He felt the use of troops for economic or imperialist consideration was wrong, a viewpoint he would carry for his entire career.

Using a quote from the above article, answer the following question: what did he study?
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Answer: Majoring in mathematics,

Problem: Ladda Tammy Duckworth (born March 12, 1968) is an American politician and retired U.S. Army Lieutenant Colonel, serving as the junior United States Senator for Illinois since 2017. A member of the Democratic Party, she earlier represented Illinois' 8th district for two terms (2013-2017) in the United States House of Representatives. Before election to office, she served as Assistant Secretary for Public and Intergovernmental Affairs in the United States Department of Veterans Affairs (2009-2011), and she was the Director of the Illinois Department of Veterans Affairs (2006-2009). In the 2016 election, Duckworth defeated incumbent Republican Senator Mark Kirk for the seat in the United States Senate.

Following in the footsteps of her father, who served in World War II, and ancestors who served in the Revolutionary War, Duckworth joined the Army Reserve Officers' Training Corps as a graduate student at George Washington University in 1990. She became a commissioned officer in the United States Army Reserve in 1992 and chose to fly helicopters because it was one of the few combat jobs open to women. As a member of the Army Reserve, she went to flight school, later transferring to the Army National Guard and entering the Illinois Army National Guard in 1996. Duckworth also worked as a staff supervisor at Rotary International headquarters in Evanston, Illinois. Duckworth was working towards a Ph.D. in political science at Northern Illinois University, with research interests in the political economy and public health in southeast Asia, when she was deployed to Iraq in 2004. She lost her right leg near the hip and her left leg below the knee from injuries sustained on November 12, 2004, when the UH-60 Black Hawk helicopter she was co-piloting was hit by a rocket-propelled grenade fired by Iraqi insurgents. She was the first American female double amputee from the Iraq war. The explosion "almost completely destroyed her right arm, breaking it in three places and tearing tissue from the back side of it". The doctors "reset the bones in her arm and stitched the cuts" to save her arm. Duckworth received a Purple Heart on December 3 and was promoted to Major on December 21 at the Walter Reed Army Medical Center, where she was presented with an Air Medal and Army Commendation Medal. She retired from the Illinois Army National Guard in October 2014 as a lieutenant colonel. She returned to school and completed a PhD in Human Services at Capella University in March 2015. The Daughters of the American Revolution erected a statue with Duckworth's likeness, and that of the Revolution's Molly Pitcher in Mount Vernon, Illinois, in 2011. The statue was erected in honor of female veterans.

When did she return from Iraq?

Answer with quotes:
Duckworth received a Purple Heart on December 3 and was promoted to Major on December 21 at the Walter Reed Army Medical Center,