Problem: Evaporation and sublimation into a vacuum is called outgassing. All materials, solid or liquid, have a small vapour pressure, and their outgassing becomes important when the vacuum pressure falls below this vapour pressure. In man-made systems, outgassing has the same effect as a leak and can limit the achievable vacuum. Outgassing products may condense on nearby colder surfaces, which can be troublesome if they obscure optical instruments or react with other materials. This is of great concern to space missions, where an obscured telescope or solar cell can ruin an expensive mission.
Why can outgassing products ruin a space mission?
The answer is the following: obscure optical instruments

Problem: Most Greeks are Christians, belonging to the Greek Orthodox Church. During the first centuries after Jesus Christ, the New Testament was originally written in Koine Greek, which remains the liturgical language of the Greek Orthodox Church, and most of the early Christians and Church Fathers were Greek-speaking. There are small groups of ethnic Greeks adhering to other Christian denominations like Greek Catholics, Greek Evangelicals, Pentecostals, and groups adhering to other religions including Romaniot and Sephardic Jews and Greek Muslims. About 2,000 Greeks are members of Hellenic Polytheistic Reconstructionism congregations.
What is the religion of the Greek majority ?
The answer is the following: Christians

Problem: In 1865, when the Bell family moved to London, Bell returned to Weston House as an assistant master and, in his spare hours, continued experiments on sound using a minimum of laboratory equipment. Bell concentrated on experimenting with electricity to convey sound and later installed a telegraph wire from his room in Somerset College to that of a friend. Throughout late 1867, his health faltered mainly through exhaustion. His younger brother, Edward "Ted," was similarly bed-ridden, suffering from tuberculosis. While Bell recovered (by then referring to himself in correspondence as "A.G. Bell") and served the next year as an instructor at Somerset College, Bath, England, his brother's condition deteriorated. Edward would never recover. Upon his brother's death, Bell returned home in 1867. His older brother Melville had married and moved out. With aspirations to obtain a degree at University College London, Bell considered his next years as preparation for the degree examinations, devoting his spare time at his family's residence to studying.
How did Bell sign his letters?
The answer is the following: A.G. Bell

Problem: As economic and demographic methods were applied to the study of history, the trend was increasingly to see the late Middle Ages as a period of recession and crisis. Belgian historian Henri Pirenne continued the subdivision of Early, High, and Late Middle Ages in the years around World War I. Yet it was his Dutch colleague, Johan Huizinga, who was primarily responsible for popularising the pessimistic view of the Late Middle Ages, with his book The Autumn of the Middle Ages (1919). To Huizinga, whose research focused on France and the Low Countries rather than Italy, despair and decline were the main themes, not rebirth.
What was the nationality of historian Henri Pirenne?
The answer is the following:
Belgian