Problem: Database:

Just as the navigational approach would require programs to loop in order to collect records, the relational approach would require loops to collect information about any one record. Codd's solution to the necessary looping was a set-oriented language, a suggestion that would later spawn the ubiquitous SQL. Using a branch of mathematics known as tuple calculus, he demonstrated that such a system could support all the operations of normal databases (inserting, updating etc.) as well as providing a simple system for finding and returning sets of data in a single operation.

What is used to solve the problem of looping?
---
A: a set-oriented language


Problem: This has led to new terms such as cyberwarfare and cyberterrorism. More and more critical infrastructure is being controlled via computer programs that, while increasing efficiency, exposes new vulnerabilities. The test will be to see if governments and corporations that control critical systems such as energy, communications and other information will be able to prevent attacks before they occur. As Jay Cross, the chief scientist of the Internet Time Group, remarked, "Connectedness begets vulnerability."
What has led to cyberwarfare? 
---
Answer: unanswerable


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
At its press conference at the 2007 Tokyo Game Show, Sony announced DualShock 3 (trademarked DUALSHOCK 3), a PlayStation 3 controller with the same function and design as Sixaxis, but with vibration capability included. Hands-on accounts describe the controller as being noticeably heavier than the standard Sixaxis controller and capable of vibration forces comparable to DualShock 2. It was released in Japan on November 11, 2007; in North America on April 5, 2008; in Australia on April 24, 2008; in New Zealand on May 9, 2008; in mainland Europe on July 2, 2008, and in the United Kingdom and Ireland on July 4, 2008.
What did many people who handled the DualShock 3 say it was compared to the Sixaxis?
A: heavier


Context and question: The top 50 m (160 ft) of a glacier are rigid because they are under low pressure. This upper section is known as the fracture zone and moves mostly as a single unit over the plastically flowing lower section. When a glacier moves through irregular terrain, cracks called crevasses develop in the fracture zone. Crevasses form due to differences in glacier velocity. If two rigid sections of a glacier move at different speeds and directions, shear forces cause them to break apart, opening a crevasse. Crevasses are seldom more than 46 m (150 ft) deep but in some cases can be 300 m (1,000 ft) or even deeper. Beneath this point, the plasticity of the ice is too great for cracks to form. Intersecting crevasses can create isolated peaks in the ice, called seracs.
Which zone is the top of the glaciers?
Answer: fracture zone


Question: The bacterial cell is surrounded by a cell membrane (also known as a lipid, cytoplasmic or plasma membrane). This membrane encloses the contents of the cell and acts as a barrier to hold nutrients, proteins and other essential components of the cytoplasm within the cell. As they are prokaryotes, bacteria do not usually have membrane-bound organelles in their cytoplasm, and thus contain few large intracellular structures. They lack a true nucleus, mitochondria, chloroplasts and the other organelles present in eukaryotic cells. Bacteria were once seen as simple bags of cytoplasm, but structures such as the prokaryotic cytoskeleton and the localization of proteins to specific locations within the cytoplasm that give bacteria some complexity have been discovered. These subcellular levels of organization have been called "bacterial hyperstructures".
Is there an answer to this question: Absence of what make bacteria belong to prokaryotes?

Answer: true nucleus, mitochondria, chloroplasts and the other organelles


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Greenhouses convert solar light to heat, enabling year-round production and the growth (in enclosed environments) of specialty crops and other plants not naturally suited to the local climate. Primitive greenhouses were first used during Roman times to produce cucumbers year-round for the Roman emperor Tiberius. The first modern greenhouses were built in Europe in the 16th century to keep exotic plants brought back from explorations abroad. Greenhouses remain an important part of horticulture today, and plastic transparent materials have also been used to similar effect in polytunnels and row covers.
Where were the first modern greenhouses built?
A:
Europe