Problem: When American 11 struck the World Trade Center at 8:46, no one in the White House or traveling with the President knew that it had been hijacked. While that information circulated within the FAA, we found no evidence that the hijacking was reported to any other agency in Washington before 8:46. Most federal agencies learned about the crash in New York from CNN. Within the FAA, the administrator, Jane Garvey, and her acting deputy, Monte Belger, had not been told of a confirmed hijacking before they learned from television that a plane had crashed. Others in the agency were aware of it, as we explained earlier in this chapter. Inside the National Military Command Center, the deputy director of operations and his assistant began notifying senior Pentagon officials of the incident. At about 9:00, the senior NMCC operations officer reached out to the FAA operations center for information. Although the NMCC was advised of the hijacking of American 11, the scrambling of jets was not discussed. In Sarasota, Florida, the presidential motorcade was arriving at the Emma E. Booker Elementary School, where President Bush was to read to a class and talk about education. White House Chief of Staff Andrew Card told us he was standing with the President outside the classroom when Senior Advisor to the President Karl Rove first informed them that a small, twin-engine plane had crashed into the World Trade Center. The President's reaction was that the incident must have been caused by pilot error. At 8:55, before entering the classroom, the President spoke to National Security Advisor Condoleezza Rice, who was at the White House. She recalled first telling the President it was a twin-engine aircraft-and then a commercial aircraft-that had struck the World Trade Center, adding "that's all we know right now, Mr. President." At the White House, Vice President Dick Cheney had just sat down for a meeting when his assistant told him to turn on his television because a plane had struck the NorthTower of the World Trade Center. The Vice President was wondering "How the hell could a plane hit the World Trade Center" when he saw the second aircraft strike the South Tower. Elsewhere in the White House, a series of 9:00 meetings was about to begin. In the absence of information that the crash was anything other than an accident, the White House staff monitored the news as they went ahead with their regular schedules.

Question: "What detail about the crash of American 11 did White House Senior Advisor Karl Rove not tell the president?"

Answer: "The crash was a pilot error"
Answer: no

Problem: Alexander earned the epithet "The Great" due to his unparalleled success as a military commander. He never lost a battle, despite typically being outnumbered. This was due to use of terrain, phalanx and cavalry tactics, bold strategy, and the fierce loyalty of his troops. The Macedonian phalanx, armed with the sarissa, a spear 6 metres (20 ft) long, had been developed and perfected by Philip II through rigorous training, and Alexander used its speed and maneuverability to great effect against larger but more disparate Persian forces. Alexander also recognized the potential for disunity among his diverse army, which employed various languages and weapons. He overcame this by being personally involved in battle, in the manner of a Macedonian king. In his first battle in Asia, at Granicus, Alexander used only a small part of his forces, perhaps 13,000 infantry with 5,000 cavalry, against a much larger Persian force of 40,000. Alexander placed the phalanx at the center and cavalry and archers on the wings, so that his line matched the length of the Persian cavalry line, about 3 km (1.86 mi). By contrast, the Persian infantry was stationed behind its cavalry. This ensured that Alexander would not be outflanked, while his phalanx, armed with long pikes, had a considerable advantage over the Persian's scimitars and javelins. Macedonian losses were negligible compared to those of the Persians. At Issus in 333 BC, his first confrontation with Darius, he used the same deployment, and again the central phalanx pushed through. Alexander personally led the charge in the center, routing the opposing army. At the decisive encounter with Darius at Gaugamela, Darius equipped his chariots with scythes on the wheels to break up the phalanx and equipped his cavalry with pikes. Alexander arranged a double phalanx, with the center advancing at an angle, parting when the chariots bore down and then reforming. The advance was successful and broke Darius' center, causing the latter to flee once again. When faced with opponents who used unfamiliar fighting techniques, such as in Central Asia and India, Alexander adapted his forces to his opponents' style. Thus, in Bactria and Sogdiana, Alexander successfully used his javelin throwers and archers to prevent outflanking movements, while massing his cavalry at the center.

Question: "How did Alexander change the use of the phalanx at the battle of Gaugamela?"

Answer: "Darius equipped his chariots with scythes on the wheels to break up the phalanx"
Answer: yes

Problem: Density is also an important physical property of matter. The concept of density combines what we know about an objects mass and volume. Density reflects how closely packed the particles of matter are. When particles are packed together more tightly, matter is more dense. Differences in density of matter explain many phenomena. It explains why helium balloons rise. It explains why currents such as the Gulf Stream flow through the oceans. It explains why some things float in or sink. You can see this in action by pouring vegetable oil into water. You can see a colorful demonstration in this video.

Question: "What is density?"

Answer: "The conductivity of an object"
Answer:
no