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: Today, nearly 400 animals are listed as threatened or endangered animals in the United States. Many are at risk of becoming extinct or disappearing permanently. Unless efforts to save these vulnerable animals succeed, many of the country's greatest creatures will be lost forever. From the facts listed, guess which animals are endangered. Click on the picture to find out more about each of these animals in trouble. American Crocodile *American crocodiles are about 12 feet long. They live on land and in shallow water, swamps and marshes. *American crocodiles like to float in the water with only their eyes and noses above the water surface. *American crocodiles eat mostly small animals, which they grab with their strong jaws and sharp teeth. *American crocodiles lay eggs. They hide their eggs under twigs and leaves, or bury them in the sand. *Some crocodiles help their young hatch, and then carry them to the water in their mouth. Habitat Southern Florida, Mexico, Central and South American, Caribbean islands. Why It's Endangered Overhunted for its skin and habitat destruction. Peninsular Bighorn Sheep *Bighorn sheep can weigh as much as 280 pounds and stand about 3 feet tall. *They live in dry, desert mountain ranges, near rocky cliffs. *Bighorn sheep eat grass, twigs and leaves. *Male sheep are called rams and can be recognized by their huge, brown horns. The horns curl back over the ears, down,and up past the cheeks. *They live in herds or groups. The male sheep with the biggest horns are usually in charge. Male horns can weigh as much as 30 pounds. *Males will use their massive horns to fight. The fights can last as long as 24 hours. *Females are called ewes. They are smaller than rams and have shorter, smaller horns. Habitat Nevada and California to west Texas and south into Mexico. Why It's Endangered Loss of habitat, hunting illegally, drought and disease. 
 Question: Where can we find both American crocodiles and Bighorn sheep according to the passage?
mexico.

Context: Rose Elliot (Irene Miracle), a poet living alone in New York City, discovers an ancient book called The Three Mothers. It tells of the existence of three evil sisters who rule the world with sorrow, tears, and darkness. The book, written by an architect named Varelli, reveals that the three dwell inside separate homes that had been specially designed and built for them by the architect in Rome, Freiburg, and New York. Rose suspects that she is living in one of the buildings and writes to her brother Mark (Leigh McCloskey), a music student in Rome, urging him to visit her. Using clues provided in Varelli's book as a guide, Rose searches the cellar of her building and discovers a hole in the floor which leads to a water-filled ballroom. After accidentally dropping her keys into the water, she enters the flooded room. Swimming under the surface, she sees a portrait bearing the words "Mater Tenebrarum" and is able to reclaim the keys. A putrid corpse suddenly rises from the depths, frightening her. She escapes, although a shadowy figure watches her leave the basement.In Rome, Mark attempts to read Rose's letter during class. He is distracted by the intense gaze of a beautiful student (Ania Pieroni). When the class ends she leaves suddenly; Mark follows, leaving the letter behind. His friend Sara (Eleonora Giorgi) picks up the letter, and eventually reads it. Horrified by the letter's contents, she takes a taxi to a library and locates a copy of The Three Mothers. While looking for an exit, Sara is attacked by a monstrous figure who recognizes the book. She throws the book to the ground and escapes. Later that night, she seeks the company of a neighbor named Carlo (Gabriele Lavia) and both are stabbed to death by a gloved killer. Mark discovers the bodies and two torn fragments from Rose's letter. After the police arrive, he walks out of Sara's apartment and sees a taxi slowly driving by. In it is the music student, staring at him intently once again.Mark telephones Rose but is unable to hear her clearly. He promises to visit just before the connection fails. Cut off, Rose sees two shadowy figures preparing to enter her apartment. She leaves through a back door, but is followed. In a decrepit room, she is grabbed from behind by a clawed assailant and brutally murdered.Upon arriving in New York, Mark meets some of the residents of Rose's building, including a nurse (Veronica Lazar) who is caring for the elderly Professor Arnold (Feodor Chaliapin, Jr.), a wheelchair-bound mute. Mark learns from the sickly Countess Elise (Daria Nicolodi) that Rose has disappeared. Elise explains how Rose had been acting strangely. After the two find blood on the carpet outside Rose's room, Mark follows the stains. He suddenly becomes ill and falls unconscious. Elise sees a black-robed figure dragging Mark away, but the figure suddenly stops and gives chase to Elise. She is attacked by dozens of cats, who bite and claw at her flesh. The hooded figure then stabs her to death. Mark staggers to the house's foyer where the nurse and caretaker (Alida Valli) put him to bed.The next day, Mark asks Kazanian (Sacha Pitoeff), the antique dealer who sold Rose the Three Mothers book, about Rose. However, the man provides no information. That night, Kazanian drowns several cats in a Central Park pond and accidentally falls into the water. Hundreds of rats from a nearby drain crawl all over him, gnawing his flesh. A hot dog vendor hears Kazanian's cries and rushes over. The man kills Kazanian with a knife.Carol, the caretaker, discovers the horribly mutilated corpse of Elise's butler (Leopoldo Mastelloni) in the Countess' apartment. Shocked, she drops a lit candle which starts a fire. Attempting to put out the flames, she becomes entangled in burning draperies and falls from a window to her death.Meanwhile, Mark uses a clue from Rose's letter to discover that beneath each floor is a secret 
 Question: Who is Rose grabbed by?
clawed assailant

Context: A covalent bond is the force of attraction that holds together two atoms that share a pair of electrons. The shared electrons are attracted to the nuclei of both atoms. Covalent bonds form only between atoms of nonmetals. The two atoms may be the same or different elements. If the bonds form between atoms of different elements, a covalent compound forms. Covalent compounds are described in detail later in the lesson. To see a video about covalent bonding, go to this URL: (6:20). MEDIA Click image to the left or use the URL below. URL: Figure 7.7 shows an example of a covalent bond forming between two atoms of the same element, in this case two atoms of hydrogen. The two atoms share a pair of electrons. Hydrogen normally occurs in two-atom, or diatomic, molecules like this (di- means "two"). Several other elements also normally occur as diatomic molecules: nitrogen, oxygen, and all but one of the halogens (fluorine, chlorine, bromine, and iodine). Covalent bonds form because they give atoms a more stable arrangement of electrons. Look at the hydrogen atoms in Figure 7.7. Alone, each hydrogen atom has just one electron. By sharing electrons with another hydrogen atom, it has two electrons: its own and the one in the other hydrogen atom. The shared electrons are attracted to both hydrogen nuclei. This force of attraction holds the two atoms together as a molecule of hydrogen. Some atoms need to share more than one pair of electrons to have a full outer energy level. For example, an oxygen atom has six valence electrons. It needs two more electrons to fill its outer energy level. Therefore, it must form two covalent bonds. This can happen in many different ways. One way is shown in Figure 7.8. The oxygen atom in the figure has covalent bonds with two hydrogen atoms. This forms the covalent compound water. In some covalent bonds, electrons are not shared equally between the two atoms. These are called polar bonds. Figure 7.9 shows this for water. The oxygen atom attracts the shared electrons more strongly because its nucleus has more positively charged protons. As a result, the oxygen atom becomes slightly negative in charge. The hydrogen atoms attract the electrons less strongly. They become slightly positive in charge. For another example of polar bonds, see the video at this URL: (0:52). MEDIA Click image to the left or use the URL below. URL: In other covalent bonds, electrons are shared equally. These bonds are called nonpolar bonds. Neither atom attracts the shared electrons more strongly. As a result, the atoms remain neutral. Figure 7.10 shows an example of nonpolar bonds. Covalent bonds between atoms of different elements form covalent compounds. The smallest, simplest covalent compounds have molecules with just two atoms. An example is hydrogen chloride (HCl). It consists of one hydrogen atom and one chlorine atom. The largest, most complex covalent molecules have thousands of atoms. Examples include proteins and carbohydrates. These are compounds in living things. Helpful Hints Naming Covalent Compounds Follow these rules in naming simple covalent compounds: The element closer to the left of the periodic table is named first. The second element gets the suffix ide. Prefixes such as di- (2) and tri- (3) show the number of each atom in the compound. These are written with subscripts in the chemical formula. Example: The gas that consists of one carbon atom and two oxygen atoms is named carbon dioxide. Its chemical formula is CO2 . You Try It! Problem: What is the name of the compound that contains three oxygen atoms and two nitrogen atoms? What is its chemical formula? Covalent compounds have different properties than ionic compounds because of their bonds. Covalent compounds exist as individual molecules rather than crystals. It takes less energy for individual molecules than ions in a crystal to pull apart. As a result, covalent compounds have lower melting and boiling points than ionic compounds. Many are gases or liquids at room temperature. Covalent compounds have shared electrons. These are not free to move like the transferred electrons of ionic 
 Question: force of attraction holding together two atoms that share a pair of electrons

covalent bond