instruction:
In this task, you will be presented with a context passage, a question about that paragraph, and a possible answer to that question. The task is to check the validity of the answer. Answer with "Yes" or "No".
question:
 Late on the next Sunday afternoon Gifford had gone for a country walk which he had arranged to bring him round in time for the evening service at the little village church of Wynford standing just outside the park boundary.  His way took him by well-remembered field-paths which, although towards the end of his walk darkness had set in, he had no difficulty in tracing.  The last field he crossed brought him to a by-road joining the highway which ran through Wynford, the junction being about a quarter of a mile from the church.  As he neared the stile which admitted to the road he saw, on the other side of the hedge and showing just above it, the head of a man.  At the sound of his footsteps the man quickly turned, and, as for a moment the fitful moonlight caught his face, Gifford was sure he recognized Gervase Henshaw.  But he took no notice and kept on his way to the stile, which he crossed and gained the road.  As he did so he glanced back.  A horse and trap was waiting there with Henshaw in it.  He was now bending down, probably with the object of concealing his identity, and had moved on a few paces farther down the road. <sep>What was Gervase doing in the field?<sep>He was covertly setting a trap
answer:
Yes


question:
Energy often changes from one form to another. For example, the drummer transfers motion to sound energy. When the moving drumstick strikes the drum head, the drum starts to vibrate. The motion of the vibrating drum head creates the sound you hear. Any form of energy can change into any other form. Frequently, one form of energy changes into two or more different forms. Have you ever sat in front of a campfire? What are two things you notice? The fire creates light. It is also warm by the fire, meaning it creates heat. The energy of the fire comes from the stored energy in the wood. The wood contains chemical energy. As it burns, the chemical energy is changed into light and heat. Not all chemical energy changes produce light and heat. Our cars use gasoline as a fuel. Gasoline contains chemical energy. When our cars burn gasoline in their engines, it is converted into motion and heat. When energy changes forms, energy is conserved. <sep>What do wood and gasoline have in common?<sep>They both contain chemical energy
answer:
Yes


question:
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. <sep>How did Alexander change the use of the phalanx at the battle of Gaugamela?<sep>Darius equipped his chariots with scythes on the wheels to break up the phalanx
answer:

Yes


