Problem: In September 1982, Prime minister Margaret Thatcher travelled to Beijing to negotiate with the Chinese government on the future of Britain's last major and most populous overseas territory, Hong Kong. Under the terms of the 1842 Treaty of Nanking, Hong Kong Island itself had been ceded to Britain in perpetuity, but the vast majority of the colony was constituted by the New Territories, which had been acquired under a 99-year lease in 1898, due to expire in 1997. Thatcher, seeing parallels with the Falkland Islands, initially wished to hold Hong Kong and proposed British administration with Chinese sovereignty, though this was rejected by China. A deal was reached in 1984—under the terms of the Sino-British Joint Declaration, Hong Kong would become a special administrative region of the People's Republic of China, maintaining its way of life for at least 50 years. The handover ceremony in 1997 marked for many, including Charles, Prince of Wales, who was in attendance, "the end of Empire".
Which treaty had given Hong Kong to Britain?
The answer is the following: Treaty of Nanking

Problem: In 550 BC, Cyrus the Great, son of Mandane and Cambyses I, took over the Median Empire, and founded the Achaemenid Empire by unifying other city states. The conquest of Media was a result of what is called the Persian Revolt. The brouhaha was initially triggered by the actions of the Median ruler Astyages, and was quickly spread to other provinces, as they allied with the Persians. Later conquests under Cyrus and his successors expanded the empire to include Lydia, Babylon, Egypt, parts of the Balkans and Eastern Europe proper, as well as the lands to the west of the Indus and Oxus rivers.
Who founded the Achaemenid Empire when the city states in Iran came together in unification?
The answer is the following: Cyrus the Great

Problem: The word gymnastics derives from the common Greek adjective γυμνός (gymnos) meaning "naked", by way of the related verb γυμνάζω (gymnazo), whose meaning is to train naked", "train in gymnastic exercise", generally "to train, to exercise". The verb had this meaning, because athletes in ancient times exercised and competed without clothing. It came into use in the 1570s, from Latin gymnasticus, from Greek gymnastikos "fond of or skilled in bodily exercise," from gymnazein "to exercise or train" (see gymnasium).
What does the  verb gymnazo mean?
The answer is the following: to train naked", "train in gymnastic exercise", generally "to train, to exercise"

Problem: Immunization against the pathogens that cause diarrheal disease is a viable prevention strategy, however it does require targeting certain pathogens for vaccination. In the case of Rotavirus, which was responsible for around 6% of diarrheal episodes and 20% of diarrheal disease deaths in the children of developing countries, use of a Rotavirus vaccine in trials in 1985 yielded a slight (2-3%) decrease in total diarrheal disease incidence, while reducing overall mortality by 6-10%. Similarly, a Cholera vaccine showed a strong reduction in morbidity and mortality, though the overall impact of vaccination was minimal as Cholera is not one of the major causative pathogens of diarrheal disease. Since this time, more effective vaccines have been developed that have the potential to save many thousands of lives in developing nations, while reducing the overall cost of treatment, and the costs to society.
What is responsible for 6% of dearrheal disease?
The answer is the following:
Rotavirus