TASK DEFINITION: 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.
PROBLEM: 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

SOLUTION: prokaryotic cell

PROBLEM: Context: My first visit to Angkor Wat was in 1980. The country had been at war for many years and _ and falling to pieces. Plants were growing out of the roofs, and trees were growing in the courtyards. Today, the temple is the scene of a busy repair program. A team of 15 Indian experts are organizing a workforce of 400 Cambodians, most of them women, who are cleaning, repairing and rebuilding parts of this temple. As I walked through the courtyards, I noticed the Cambodian women devote hours to cleaning carefully a tiny area of stone. Boards are laid down to protect the precious painted stones while the repair work is going on. There are very few machines and little heavy equipment. Workers carry building materials in buckets at the end of long poles. Piles of stones lie in a corner of the courtyard, waiting to be replaced. The work of cleaning the stones is watched over by three Indian chemists. It is a very slow task. First they clean the stones with brushes using buckets of a weak chemical. Then gaps between the stones are filled in. Finally another material is painted onto the stones which will protect them from water forever. Work starts every day at 7 a. m. and goes on until late afternoon six days a week, with a break at midday. Evening is the best time to visit the temple, after the tour groups have left. As the sun sinks lower, shadows spread across the courtyard. After sunset, the sky turns pink. The grey stone towers take on a golden color before turning pink. Nowhere else in the world can there be such a quiet, beautiful place. 
 Question: To clean the stone, how many steps should be followed?

SOLUTION: three

PROBLEM: Context: Ten-year-old Chihiro (voice: Daveigh Chase in the 2002 English dub) and her parents (voices: Lauren Holly and Michael Chiklis) drive to their new home. Chihiro is whiny and unhappy about the move, especially when she notices that the bouquet her friend gave her as a good-bye gift is wilting. In sight of their new house, they take a wrong turn and follow a bumpy, decayed old road through the woods; Chihiro sees an odd old statue through the trees as they drive by. The road ends at a tunnel leading to an abandoned theme park. It gives Chihiro the creeps, but her parents persuade her to go in with them and look around.After wandering across a grassy landscape and a dry riverbed, they climb a stone staircase and come to a street lined with restaurants and shops. Most are deserted, but the aroma of cooking leads them to the one restaurant that's well stocked with food -- though it's mysteriously deserted. Mom and Dad are hungry and start eating, despite Chihiro's objections. The food is delicious, and Chihiro wanders away to explore while they eat. She finds a towering, ornate building that she recognizes as a bathhouse (a spa resort); there's a train track running under it. She meets a boy (voice: Jason Marsden) in traditional dress who is alarmed to see her; he tells her to leave and get back across the river before it gets dark. Chihiro runs back to her parents, but they're still eating -- and they've turned into pigs. Strange, dark, ghostly figures appear in all the shops and streets, frightening Chihiro and separating her from the pigs that were her parents. Chihiro runs back to the river, which was nearly dry when they came over but is now full and large, and she doesn't even recognize the buildings on the far side. As a riverboat approaches, she notices that her body has become transparent.The riverboat lands a big crowd of people in costume -- or maybe they're not people; at first they're only visible as paper masks. Chihiro thinks shes dreaming, but can't wake up. The boy who warned her away finds her and tells her she must eat some food from his world or she'll fade away. He assures her that she won't turn into a pig. She swallows the morsel he gives her and becomes solid, but finds that she's stuck to the ground until he recites an incantation to release her. A bird with a woman's head flies above them and he hides her, saying the bird is looking for her. They run through alleys and the pig barn to the big bathhouse, which is accessed by a bridge; the boy says she has to hold her breath as they cross the bridge or the spell that makes her invisible will be broken. Customers -- fantastically varied gods and spirits -- are crossing the bridge and being greeted by bathhouse staff. Chihiro makes it almost all the way across, but a frog (voice: Bob Bergen) that speaks to her companion (calling him Haku) startles her and she takes a breath. Luckily only the frog seems to see her, and Haku uses magic to encase it in a bubble to shut it up.Haku tells her to find Kamajii (voice: David Ogden Stiers), the boiler man, and make him give her a job; she must have a job to stay at the bathhouse, or else Yubaba (voice: Suzanne Pleshette), the old witch who rules the bathhouse, will turn her into an animal. And Haku says she has to stay if she wants to find and help her parents, who are still pigs, wherever they are. He knows her name and says he's known her since she was very small.Chihiro descends a steep, winding, rail-less wooden stairway in search of Kamajii and the boiler room. When she finds them, she sees a weird set-up in which the boiler is fed by creatures like spiders (delivering coal one lump at a time) and the machinery is controlled by a bearded, bald man 
 Question: who does Sen invite inside

SOLUTION:
no face