Input: Read this: The hole walls for boards with two or more layers can be made conductive and then electroplated with copper to form plated-through holes. These holes electrically connect the conducting layers of the PCB. For multi-layer boards, those with three layers or more, drilling typically produces a smear of the high temperature decomposition products of bonding agent in the laminate system. Before the holes can be plated through, this smear must be removed by a chemical de-smear process, or by plasma-etch. The de-smear process ensures that a good connection is made to the copper layers when the hole is plated through. On high reliability boards a process called etch-back is performed chemically with a potassium permanganate based etchant or plasma. The etch-back removes resin and the glass fibers so that the copper layers extend into the hole and as the hole is plated become integral with the deposited copper.
Question: What's the minimum number of layers a PCB can have to be considered "multi-layer"?

Output: three

QUES: In early February, the South Korean 11th Division ran the operation to destroy the guerrillas and their sympathizer citizens in Southern Korea. During the operation, the division and police conducted the Geochang massacre and Sancheong-Hamyang massacre. In mid-February, the PVA counterattacked with the Fourth Phase Offensive and achieved initial victory at Hoengseong. But the offensive was soon blunted by the IX Corps positions at Chipyong-ni in the center. Units of the U.S. 2nd Infantry Division and the French Battalion fought a short but desperate battle that broke the attack's momentum. The battle is sometimes known as the Gettysburg of the Korean War. The battle saw 5,600 Korean, American and French troops defeat a numerically superior Chinese force. Surrounded on all sides, the U.S. 2nd Infantry Division Warrior Division's 23rd Regimental Combat Team with an attached French Battalion was hemmed in by more than 25,000 Chinese Communist forces. United Nations forces had previously retreated in the face of large Communist forces instead of getting cut off, but this time they stood and fought at odds of roughly 15 to 1.

Who's attack resulted in victory at Hoengseong?
What is the answer?
ANS: the PVA

QUES: The Freeview HD service currently contains 10 HD channels (as of December 2013[update]) and was rolled out region by region across the UK in accordance with the digital switchover process, finally being completed in October 2012. However, Freeview HD is not the first HDTV service over digital terrestrial television in Europe;
Which service contains 10 HD channels and finished its roll out in October 2012?

ANS: Freeview HD

A strong and prominent a cappella tradition was begun in the midwest part of the United States in 1911 by F. Melius Christiansen, a music faculty member at St. Olaf College in Northfield, Minnesota. The St. Olaf College Choir was established as an outgrowth of the local St. John's Lutheran Church, where Christiansen was organist and the choir was composed, at least partially, of students from the nearby St. Olaf campus. The success of the ensemble was emulated by other regional conductors, and a rich tradition of a cappella choral music was born in the region at colleges like Concordia College (Moorhead, Minnesota), Augustana College (Rock Island, Illinois), Wartburg College (Waverly, Iowa), Luther College (Decorah, Iowa), Gustavus Adolphus College (St. Peter, Minnesota), Augustana College (Sioux Falls, South Dakota), and Augsburg College (Minneapolis, Minnesota). The choirs typically range from 40 to 80 singers and are recognized for their efforts to perfect blend, intonation, phrasing and pitch in a large choral setting.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): How many singers are typically in the choirs?
Ah, so.. 40 to 80

Question: In modern-day Germany, the Holy Roman Empire continued to rule, but the elective nature of the imperial crown meant there was no enduring dynasty around which a strong state could form. Further east, the kingdoms of Poland, Hungary, and Bohemia grew powerful. In Iberia, the Christian kingdoms continued to gain land from the Muslim kingdoms of the peninsula; Portugal concentrated on expanding overseas during the 15th century, while the other kingdoms were riven by difficulties over royal succession and other concerns. After losing the Hundred Years' War, England went on to suffer a long civil war known as the Wars of the Roses, which lasted into the 1490s and only ended when Henry Tudor (r. 14851509 as Henry VII) became king and consolidated power with his victory over Richard III (r. 148385) at Bosworth in 1485. In Scandinavia, Margaret I of Denmark (r. in Denmark 13871412) consolidated Norway, Denmark, and Sweden in the Union of Kalmar, which continued until 1523. The major power around the Baltic Sea was the Hanseatic League, a commercial confederation of city states that traded from Western Europe to Russia. Scotland emerged from English domination under Robert the Bruce (r. 130629), who secured papal recognition of his kingship in 1328.
Try to answer this question if possible: Along with Denmark and Sweden, what country was part of the Union of Kalmar?
Answer: Norway

Question: Hunter-gatherer societies manifest significant variability, depending on climate zone/life zone, available technology and societal structure. Archaeologists examine hunter-gatherer tool kits to measure variability across different groups. Collard et al. (2005) found temperature to be the only statistically significant factor to impact hunter-gatherer tool kits. Using temperature as a proxy for risk, Collard et al.'s results suggest that environments with extreme temperatures pose a threat to hunter-gatherer systems significant enough to warrant increased variability of tools. These results support Torrence's (1989) theory that risk of failure is indeed the most important factor in determining the structure of hunter-gatherer toolkits.
Try to answer this question if possible: Risk of success is the most important factor in determining the structure of whose toolkits?
Answer:
unanswerable