input: After Park Jin-young revealed the name of his first girl group Wonder Girls in May 2006, the Wonder Girls were introduced through a TV show titled MTV Wonder Girls. The first four episodes outlined the characteristics and profiles of each member. Shortly after selecting Yeeun as the fifth member, the Wonder Girls held their first showcase in the MTV Studio. They performed a cover version of "Don't Cha" by the Pussycat Dolls as well as original songs, including "Irony" and "mianhan maeum" ("It's Not Love"). Sunye sang her version of Destiny's Child's "Stand Up for Love", while Hyuna performed a showcase of her dancing skills. The other three members--Yeeun, Sunmi and Sohee--performed a cover version of Janet Jackson's "Together Again".  The Wonder Girls officially debuted in early 2007 on MBC's Show! Music Core, performing "Irony", the hip-hop single from their first album, The Wonder Begins. The album sold 11,454 physical copies in 2007. Shortly after, "Wonderfuls", the official Wonder Girls fanclub, was established. The group held several showcases in China after receiving Chinese lessons. In mid-2007, however, members of the Wonder Girls were beset by various injuries and health problems. On June 25, Sohee was sidelined for a month after tearing a knee ligament in a fall from a running motorcycle during the filming of her movie, ddeugeoun geosi joha (I Like It Hot).  The remaining four members continued performing until late July, when Hyuna was withdrawn from the group by her parents due to their concern over her problems with chronic gastroenteritis and fainting spells. In autumn 2007, the talent agency Good Entertainment sent their trainee Yubin to JYP Entertainment as a replacement for Hyuna. She made her debut three days later in the group's live performance of "Tell Me" on Music Bank.  Their first full-length album, The Wonder Years, was released the following week with "Tell Me" as the lead single. Due to the last-minute addition of Yubin, the album version does not contain her part. However, the performance version of the song was reworked to include a bridge with rapping by Yubin. The single was a hit and reached number one on various Korean television and internet music charts, including KBS's Music Bank. The song also became a number one hit in Thailand. The choreography for the song was simple and widely imitated: by October, many fan performances of the dance circulated on video sharing sites such as YouTube and Daum, including one by a group of policemen who were eventually profiled on SBS's Star King. The dance's popularity was immense and the explosive attention it received became widely known as the "Tell Me Virus", earning the group the title of "Nation's Little Sisters". The Wonder Girls had an extensive promotional schedule for their album, and in late 2007 they began performing their second single, "i babo" ("This Fool"). MTV also began broadcasting The Wonder Life, a reality TV series starring the girls.

Answer this question "What was their lineup change?"
output: Hyuna was withdrawn from the group by her parents due to their concern over her problems with chronic gastroenteritis and fainting spells.

input: Nixon laid the groundwork for his overture to China before he became president, writing in Foreign Affairs a year before his election: "There is no place on this small planet for a billion of its potentially most able people to live in angry isolation." Assisting him in this venture was his National Security Advisor and future Secretary of State, Henry Kissinger, with whom the President worked closely, bypassing Cabinet officials. With relations between the Soviet Union and China at a nadir--border clashes between the two took place during Nixon's first year in office--Nixon sent private word to the Chinese that he desired closer relations. A breakthrough came in early 1971, when Chairman Mao invited a team of American table tennis players to visit China and play against top Chinese players. Nixon followed up by sending Kissinger to China for clandestine meetings with Chinese officials. On July 15, 1971, it was simultaneously announced by Beijing and by Nixon (on television and radio) that the President would visit China the following February. The announcements astounded the world. The secrecy allowed both sets of leaders time to prepare the political climate in their countries for the contact.  In February 1972, Nixon and his wife traveled to China. Kissinger briefed Nixon for over 40 hours in preparation. Upon touching down, the President and First Lady emerged from Air Force One and greeted Chinese Premier Zhou Enlai. Nixon made a point of shaking Zhou's hand, something which then-Secretary of State John Foster Dulles had refused to do in 1954 when the two met in Geneva. Over 100 television journalists accompanied the president. On Nixon's orders, television was strongly favored over printed publications, as Nixon felt that the medium would capture the visit much better than print. It also gave him the opportunity to snub the print journalists he despised.  Nixon and Kissinger met for an hour with Mao and Zhou at Mao's official private residence, where they discussed a range of issues. Mao later told his doctor that he had been impressed by Nixon, whom he considered forthright, unlike the leftists and the Soviets. He said he was suspicious of Kissinger, though the National Security Advisor referred to their meeting as his "encounter with history". A formal banquet welcoming the presidential party was given that evening in the Great Hall of the People. The following day, Nixon met with Zhou; the joint communique following this meeting recognized Taiwan as a part of China, and looked forward to a peaceful solution to the problem of reunification. When not in meetings, Nixon toured architectural wonders including the Forbidden City, Ming Tombs, and the Great Wall. Americans received their first glimpse into Chinese life through the cameras which accompanied Pat Nixon, who toured the city of Beijing and visited communes, schools, factories, and hospitals.  The visit ushered in a new era of Sino-American relations. Fearing the possibility of a Sino-American alliance, the Soviet Union yielded to pressure for detente with the United States.

Answer this question "When did Nixon visit China?"
output:
In February 1972, Nixon and his wife traveled to China.