Question: What Chinese city shares a border with the city that hosted the 2009 ELEXCON fair?

full_context: Document 1: BeiDou: The second generation of the system, officially called the BeiDou Navigation Satellite System (BDS) and also known as COMPASS or BeiDou-2, will be a global satellite navigation system consisting of 35 satellites, and is under construction as of January 2015[update]. It became operational in China in December 2011, with 10 satellites in use, and began offering services to customers in the Asia-Pacific region in December 2012. It is planned to begin serving global customers upon its completion in 2020.
Document 2: New Delhi: The 2011 World Wealth Report ranks economic activity in New Delhi at 39, but overall the capital is ranked at 37, above cities like Jakarta and Johannesburg. New Delhi with Beijing shares the top position as the most targeted emerging markets retail destination among Asia-Pacific markets.
Document 3: Dongguan: Dongguan's city administration is considered especially progressive in seeking foreign direct investment. Dongguan ranks behind only Shenzhen, Shanghai and Suzhou in exports among Chinese cities, with $65.54 billion in shipments. It is also home to one of the world's largest shopping malls, the New South China Mall, which is seeing increased activity. Although the city is geographically and thus culturally Cantonese in the Weitou form and as well as culturally Hakka in the prefectures of Fenggang and Qingxi, the majority of the modern-day population speaks Mandarin due to the large influx of economic migrants from other parts of China.
Document 4: Department store: Since the opening policy in 1979, the Chinese department stores also develops swiftly along with the fast-growing economy. There are different department store groups dominating different regions. For example, INTIME department store has the biggest market presence in Zhejiang province, while Jinying department stores dominate Jiangsu Province. Besides, there are many other department store groups, such as Pacific, Parkson, Wangfujing，New World，etc., many of them are expanding quickly by listing in the financial market.
Document 5: Melbourne: Over two-thirds of Melburnians speak only English at home (68.1%). Chinese (mainly Cantonese and Mandarin) is the second-most-common language spoken at home (3.6%), with Greek third, Italian fourth and Vietnamese fifth, each with more than 100,000 speakers. Although Victoria's net interstate migration has fluctuated, the population of the Melbourne statistical division has grown by about 70,000 people a year since 2005. Melbourne has now attracted the largest proportion of international overseas immigrants (48,000) finding it outpacing Sydney's international migrant intake on percentage, along with having strong interstate migration from Sydney and other capitals due to more affordable housing and cost of living.
Document 6: BeiDou: On July 25, 2015, the 18th and 19th satellites were successfully launched from the Xichang Satellite Launch Center, marking the first time for China to launch two satellites at once on top of a Long March 3B/Expedition-1 carrier rocket. The Expedition-1 is an independent upper stage capable of delivering one or more spacecraft into different orbits.
Document 7: Zhejiang: Zhejiang is mountainous and has therefore fostered the development of many distinct local cultures. Linguistically speaking, Zhejiang is extremely diverse. Most inhabitants of Zhejiang speak Wu, but the Wu dialects are very diverse, especially in the south, where one valley may speak a dialect completely unintelligible to the next valley a few kilometers away. Other varieties of Chinese are spoken as well, mostly along the borders; Mandarin and Huizhou dialects are spoken on the border with Anhui, while Min dialects are spoken on the border with Fujian. (See Hangzhou dialect, Shaoxing dialect, Ningbo dialect, Wenzhou dialect, Taizhou dialect, Jinhua dialect, and Quzhou dialect for more information).
Document 8: BeiDou: Unlike the American GPS, Russian GLONASS, and European Galileo systems, which use medium Earth orbit satellites, BeiDou-1 uses satellites in geostationary orbit. This means that the system does not require a large constellation of satellites, but it also limits the coverage to areas on Earth where the satellites are visible. The area that can be serviced is from longitude 70°E to 140°E and from latitude 5°N to 55°N. A frequency of the system is 2491.75 MHz.
Document 9: Wanjiang Subdistrict: Wanjiang Subdistrict () is a subdistrict of the city of Dongguan, Guangdong Province, China. It is also the home of the world's largest shopping mall, New South China Mall.
Document 10: Zhejiang: Throughout history there have been a series of lingua francas in the area to allow for better communication. The dialects spoken in Hangzhou, Shaoxing, and Ningbo have taken on this role historically. Since the founding of the People's Republic of China in 1949, Mandarin, which is not mutually intelligible with any of the local dialects, has been promoted as the standard language of communication throughout China. As a result, most of the population now can, to some degree, speak and comprehend Mandarin and can code-switch when necessary. A majority of the population educated since 1978 can speak Mandarin. Urban residents tend to be more fluent in Mandarin than rural people. Nevertheless, a Zhejiang accent is detectable in almost everyone from the area communicating in Mandarin, and the home dialect remains an important part of the everyday lives and cultural identities of most Zhejiang residents.
Document 11: BeiDou: The first satellite, BeiDou-1A, was launched on 30 October 2000, followed by BeiDou-1B on 20 December 2000. The third satellite, BeiDou-1C (a backup satellite), was put into orbit on 25 May 2003. The successful launch of BeiDou-1C also meant the establishment of the BeiDou-1 navigation system.
Document 12: BeiDou: In December 2011, Xinhua stated that "[t]he basic structure of the Beidou system has now been established, and engineers are now conducting comprehensive system test and evaluation. The system will provide test-run services of positioning, navigation and time for China and the neighboring areas before the end of this year, according to the authorities." The system became operational in the China region that same month. The global navigation system should be finished by 2020. As of December 2012, 16 satellites for BeiDou-2 have been launched, 14 of them are in service.
Document 13: BeiDou: In 2008, a BeiDou-1 ground terminal cost around CN¥20,000RMB (US$2,929), almost 10 times the price of a contemporary GPS terminal. The price of the terminals was explained as being due to the cost of imported microchips. At the China High-Tech Fair ELEXCON of November 2009 in Shenzhen, a BeiDou terminal priced at CN¥3,000RMB was presented.
Document 14: BeiDou: There are two levels of service provided — a free service to civilians and licensed service to the Chinese government and military. The free civilian service has a 10-meter location-tracking accuracy, synchronizes clocks with an accuracy of 10 nanoseconds, and measures speeds to within 0.2 m/s. The restricted military service has a location accuracy of 10 centimetres, can be used for communication, and will supply information about the system status to the user. To date, the military service has been granted only to the People's Liberation Army and to the Military of Pakistan.
Document 15: BeiDou: In 2007, the official Xinhua News Agency reported that the resolution of the BeiDou system was as high as 0.5 metres. With the existing user terminals it appears that the calibrated accuracy is 20m (100m, uncalibrated).
ground_truth: Dongguan
sub_queries: Where was the ELEXCON fair held in 2009? Answer: Shenzhen
Shenzhen >> shares border with Answer: Dongguan