Context and question: As civil wars engulfed several Central American countries in the 1980s, hundreds of thousands of Salvadorans fled their country and came to the United States. Between 1980 and 1990, the Salvadoran immigrant population in the United States increased nearly fivefold from 94,000 to 465,000. The number of Salvadoran immigrants in the United States continued to grow in the 1990s and 2000s as a result of family reunification and new arrivals fleeing a series of natural disasters that hit El Salvador, including earthquakes and hurricanes. By 2008, there were about 1.1 million Salvadoran immigrants in the United States.
How many  Salvadorans  are in America now?
Answer: By 2008, there were about 1.1 million Salvadoran immigrants in the United States.
Context and question: The Slavs under name of the Antes and the Sclaveni make their first appearance in Byzantine records in the early 6th century. Byzantine historiographers under Justinian I (527–565), such as Procopius of Caesarea, Jordanes and Theophylact Simocatta describe tribes of these names emerging from the area of the Carpathian Mountains, the lower Danube and the Black Sea, invading the Danubian provinces of the Eastern Empire.
When did Procopius of Caesarea live?
Answer: unanswerable
Context and question: Starting in 2006, Apple's industrial design shifted to favor aluminum, which was used in the construction of the first MacBook Pro. Glass was added in 2008 with the introduction of the unibody MacBook Pro. These materials are billed as environmentally friendly. The iMac, MacBook Pro, MacBook Air, and Mac Mini lines currently all use aluminum enclosures, and are now made of a single unibody. Chief designer Jonathan Ive continues to guide products towards a minimalist and simple feel, including eliminating of replaceable batteries in notebooks. Multi-touch gestures from the iPhone's interface have been applied to the Mac line in the form of touch pads on notebooks and the Magic Mouse and Magic Trackpad for desktops.
Which material did Apple add with the 2009 unibody MacBrook Pro?
Answer:
unanswerable