Context: Houston was the headquarters of Continental Airlines until its 2010 merger with United Airlines with headquarters in Chicago; regulatory approval for the merger was granted in October of that year. Bush Intercontinental became United Airlines' largest airline hub. The airline retained a significant operational presence in Houston while offering more than 700 daily departures from the city. In early 2007, Bush Intercontinental Airport was named a model "port of entry" for international travelers by U.S. Customs and Border Protection.

Question: Until 2010, which airline made Houston its headquarters?
Answer: Continental Airlines

Question: Where is United Airlines' largest air hub?
Answer: Bush Intercontinental

Question: With which airline did Continental Airlines merge?
Answer: United Airlines

Question: How many daily flights did United Airlines offer from Houston?
Answer: 700

Question: In what year was Bush Intercontinental named a model by U.S. Customs?
Answer: 2007

Question: Until 2010, which airline made Texas its headquarters?
Answer: Unanswerable

Question:  Where is United Airlines' smallest air hub?
Answer: Unanswerable

Question:  With which airline did Continental Airlines separate?
Answer: Unanswerable

Question:  How many daily flights did United Airlines offer from Texas?
Answer: Unanswerable