Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Context: Ponds are small bodies of fresh water that usually have no outlet; ponds are often are fed by underground springs. Like lakes, ponds are bordered by hills or low rises so the water is blocked from flowing directly downhill. Lakes are larger bodies of water. Lakes are usually fresh water, although the Great Salt Lake in Utah is just one exception. Water usually drains out of a lake through a river or a stream and all lakes lose water to evaporation. Lakes form in a variety of different ways: in depressions carved by glaciers, in calderas (Figure 1.1), and along tectonic faults, to name a few. Subglacial lakes are even found below a frozen ice cap. As a result of geologic history and the arrangement of land masses, most lakes are in the Northern Hemisphere. In fact, more than 60% of all the worlds lakes are in Canada most of these lakes were formed by the glaciers that covered most of Canada in the last Ice Age (Figure 1.2). Lakes are not permanent features of a landscape. Some come and go with the seasons, as water levels rise and fall. Over a longer time, lakes disappear when they fill with sediments, if the springs or streams that fill them diminish, (a) Crater Lake in Oregon is in a volcanic caldera. Lakes can also form in volcanic craters and impact craters. (b) The Great Lakes fill depressions eroded as glaciers scraped rock out from the landscape. (c) Lake Baikal, ice coated in winter in this image, formed as water filled up a tectonic faults. Lakes near Yellowknife were carved by glaciers during the last Ice Age. or if their outlets grow because of erosion. When the climate of an area changes, lakes can either expand or shrink (Figure 1.3). Lakes may disappear if precipitation significantly diminishes. Large lakes have tidal systems and currents, and can even affect weather patterns. The Great Lakes in the United States contain 22% of the worlds fresh surface water (Figure 1.1). The largest them, Lake Superior, has a tide that rises and falls several centimeters each day. The Great Lakes are large enough to alter the weather system in Northeastern United States by the lake effect, which is an increase in snow downwind of the relatively warm lakes. The Great Lakes are home to countless species of fish and wildlife. Many lakes are not natural, but are human-made. People dam a stream in a suitable spot and then let the water back up behind it, creating a lake. These lakes are called "reservoirs." Click image to the left or use the URL below. URL: 
 Question: which of these is not full of fresh water?
the great salt lake

Context: Circular RNAs (circRNAs) are a class of newly-identified non-coding RNA molecules. CircRNAs are conserved across different species and display specific organization, sequence, and expression in disease. Moreover, circRNAs' closed ring structure, insensitivity to RNase, and stability are advantages over linear RNAs in terms of development and application as a new kind of clinical marker. In addition, according to recent studies, circular RNA-7 (ciRS-7) acts as a sponge of miR-7 and thus inhibits its activity. Numerous evidences have confirmed expression of miR-7 is dysregulated in cancer tissues, however, whether ciRS-7 invovled in oncogenesis by acting as sponge of miR-7 remains unclear. Most recently, a study reported ciRS-7 acted as an oncogene in hepatocellular carcinoma through targeting miR-7 expression. This suggest ciRS-7/ miR-7 axis affects oncogenesis, and it provides a new perspective on the mechanisms of decreased miR-7 expression in cancer tissues. Discovery of sponge role of circRNAs caused researchers to more closely explore the underlying mechanism of carcinogenesis and has significant clinical implications, and may open a new chapter in research on the pathology and treatment of cancers. This review summarizes the structure and function of circRNAs and provides evidence for the impact of ciRS-7 in promoting the development of cancer by acting as sponge of miR-7. 
 Question: Which miRNA is associated with the circular RNA ciRS-7?
mir-7

Context: When he was still a child, Iwatake's father was lost at sea off Hawaii. With no food, his family was forced to move to Japan, where Iwatake joined the army during the war. He lost a brother when the bomb fell on Hiroshima. But over all the time one thing has remained unchanged. His parents bought a Christmas tree in 1937, and his family brings it out every Christmas since then, even when doing so meat risking arrest. "This tree was a shining light, because it was a symbol of unity in my family," Iwatake said as he and his wife put the final touches on the tree, which is about 3 - foot - tall. They took it out once again this year, "We have put this tree up every year for 70 years." Though he considers himself Buddhist, Iwatake was raised in a Christian tradition. He still keeps a photo of the tiny wooden church in Mauri where he and his five brothers went to church services and Sunday school. Christmas was always a special time. His father worked at a store, and Iwatake remembers the day he came home with a tree. It was nothing all that special, just metal - and - plastic, the kind of decoration that can easily be placed on a table, or in a corner somewhere. He got a string of lights, too, the kind with the big bulbs . Soon after, his father died in a fishing accident. His body was never found. Iwatake's mother had s in Japan, and took Iwatake's younger brothers there. Iwatake stayed behind to graduate from high school. In 1941, six months before Pearl Harbor , he moved to Japan as well. "Things were bad," he said. "There were war clouds hanging everywhere." 
 Question: What caused the death of Iwatake's father?

an accident.