Question: Under the Qing dynasty (1644–1911), the Nanjing area was known as Jiangning (江寧) and served as the seat of government for the Viceroy of Liangjiang. It had been visited by the Kangxi and Qianlong emperors a number of times on their tours of the southern provinces. Nanjing was invaded by British troops during the close of the First Opium War, which was ended by the Treaty of Nanjing in 1842. As the capital of the brief-lived rebel Taiping Heavenly Kingdom (founded by the Taiping rebels in the mid-19th century, Nanjing was known as Tianjing (天京, "Heavenly Capital" or "Capital of Heaven").
Is there an answer to this question: What emperors visited Nanjing more than once?

Answer: the Kangxi and Qianlong emperors


Question: One distinctive feature that has caused a great amount of interest among linguists is what is traditionally seen as three degrees of phonemic length: short, long, and "overlong", such that /sɑdɑ/, /sɑˑdɑ/ and /sɑːdɑ/ are distinct. In actuality, the distinction is not purely in the phonemic length, and the underlying phonological mechanism is still disputed.[citation needed]
Is there an answer to this question: Underlong is a degree of what length? 

Answer: unanswerable


Question: Plant responses to climate and other environmental changes can inform our understanding of how these changes affect ecosystem function and productivity. For example, plant phenology can be a useful proxy for temperature in historical climatology, and the biological impact of climate change and global warming. Palynology, the analysis of fossil pollen deposits in sediments from thousands or millions of years ago allows the reconstruction of past climates. Estimates of atmospheric CO2 concentrations since the Palaeozoic have been obtained from stomatal densities and the leaf shapes and sizes of ancient land plants. Ozone depletion can expose plants to higher levels of ultraviolet radiation-B (UV-B), resulting in lower growth rates. Moreover, information from studies of community ecology, plant systematics, and taxonomy is essential to understanding vegetation change, habitat destruction and species extinction.
Is there an answer to this question: What causes lower growth in plants?

Answer: Ozone depletion


Question: When their migratory movements ended, there appeared among the Slavs the first rudiments of state organizations, each headed by a prince with a treasury and a defense force. Moreover, it was the beginnings of class differentiation, and nobles pledged allegiance either to the Frankish/ Holy Roman Emperors or the Byzantine Emperors.
Is there an answer to this question: When did the first rudiments of state organizations appear among the Slavs?

Answer:
When their migratory movements ended