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: The Narym River is a river in the Eastern Kazakhstan, a tributary of the Irtysh River, originating at the junction of the ridges Narym and Sarymsakty of wetland formed by the mountain runoff streams. 
 Question: The body of water that Narym River is near is what?
irtysh river

Context: Cells were first discovered in the mid-1600s. The cell theory came about some 200 years later. You can see a re- enactment of some of the discoveries that led to the cell theory in this video: MEDIA Click image to the left or use the URL below. URL: British scientist Robert Hooke first discovered cells in 1665. He was one of the earliest scientists to study living things under a microscope. He saw that cork was divided into many tiny compartments, like little rooms. (Do the cells in Figure 3.1 look like little rooms to you too?) Hooke called these little rooms cells. Cork comes from trees, so what Hooke observed was dead plant cells. In the late 1600s, Dutch scientist Anton van Leeuwenhoek made more powerful microscopes. He used them to observe cells of other organisms. For example, he saw human blood cells and bacterial cells. Over the next century, microscopes were improved and more cells were observed. By the early 1800s, scientists had seen cells in many different types of organisms. Every organism that was examined was found to consist of cells. From all these observations, German scientists Theodor Schwann and Matthias Schleiden drew two major conclusions about cells. They concluded that: cells are alive. all living things are made of cells. Around 1850, a German doctor named Rudolf Virchow was observing living cells under a microscope. As he was watching, one of the cells happened to divide. Figure 3.2 shows a cell dividing, like the cell observed by Virchow. This was an aha moment for Virchow. He realized that living cells produce new cells by dividing. This was evidence that cells arise from other cells. The work of Schwann, Schleiden, and Virchow led to the cell theory. This is one of the most important theories in life science. The cell theory can be summed up as follows: All organisms consist of one or more cells. Cells are alive and the site of all life processes. All cells come from pre-existing cells. All cells have certain parts in common. These parts include the cell membrane, cytoplasm, DNA, and ribosomes. The cell membrane is a thin coat of phospholipids that surrounds the cell. Its like the skin of the cell. It forms a physical boundary between the contents of the cell and the environment outside the cell. It also controls what enters and leaves the cell. The cell membrane is sometimes called the plasma membrane. Cytoplasm is the material inside the cell membrane. It includes a watery substance called cytosol. Besides water, cytosol contains enzymes and other substances. Cytoplasm also includes other cell structures suspended in the cytosol. DNA is a nucleic acid found in cells. It contains genetic instructions that cells need to make proteins. Ribosomes are structures in the cytoplasm where proteins are made. They consist of RNA and proteins. These four components are found in all cells. They are found in the cells of organisms as different as bacteria and people. How did all known organisms come to have such similar cells? The answer is evolution. The similarities show that all life on Earth evolved from a common ancestor. Besides the four parts listed above, many cells also have a nucleus. The nucleus of a cell is a structure enclosed by a membrane that contains most of the cells DNA. Cells are classified in two major groups based on whether or not they have a nucleus. The two groups are prokaryotic cells and eukaryotic cells. Prokaryotic cells are cells that lack a nucleus. The DNA in prokaryotic cells is in the cytoplasm, rather than enclosed within a nuclear membrane. All the organisms in the Bacteria and Archaea Domains have prokaryotic cells. No other organisms have this type of cell. Organisms with prokaryotic cells are called prokaryotes. They are all single-celled organisms. They were the first type of organisms to evolve. They are still the most numerous organisms today. You can see a model of a prokaryotic cell in Figure 3.3. The cell in the figure is a bacterium. Notice how it contains a cell membrane, cytoplasm, ribosomes, and several other structures. However, the cell lacks a nucleus. The cells DNA is circular. 
 Question: ______cell that lacks a nucleus
prokaryotic cell

Context: It was the summer of 1965. DeLuca, then 17, visited Peter Buck, a family friend. Buck asked DeLuca about his plans for the future. "I'm going to college, but I need a way to pay for it," DeLuca recalls saying. "Buck said, 'You should open a sandwich shop.'" That afternoon, they agreed to be partners. And they set a goal: to open 32 stores in ten years. After doing some research, buck wrote a check for $1000. DeLuca rented a storefront in Connecticut, and when they couldn't cover their start-up costs, Buck kicked in another $1000. But business didn't go smoothly as they expected. DeLuca says, "After six months, we were doing poorly, but we didn't know how badly, because we didn't have any financial controls." All he and Buck knew was that their sales were lower than their costs. DeLuca was managing the store and going to the University of Bridgeport at the same time. Buck was working at his day job as a nuclear physicist in New York. They'd meet Monday evenings and brainstorm ideas for keeping the business running. "We convinced ourselves to open a second store. We figured we could tell the public, 'We are so successful, we are opening a second store.'" And they did--in the spring of 1966. Still, it was a lot of learning by trial and error. But the partners' learn-as-you-go approach turned out to be their greatest strength. Every Friday, DeLuca would drive around and hand-deliver the checks to pay their suppliers. "It probably took me two and a half hours and it wasn't necessary, but as a result, the suppliers got to know me very well, and the personal relationships established really helped out," DeLuca says. And having a goal was also important. "There are so many problems that can get you down. You just have to keep working toward your goal," DeLuca adds. DeLuca ended up founding Subway Sandwich, the multimillion-dollar restaurant chain. 
 Question: What contribute most to their success according to the author?

learning by trial and error.