Read the following passage  and mark the letter (A, B, C or D) on your answer sheet to indicate the correct answer to each for  the questions. 
 
Line Europeans who arrived in the Americas, the first American Indians were immigrants. Because Indians were nomadic hunters and gatherers, they probably arrived in search of new hunting grounds from Asia when they crossed the ice-covered Bering Strait to Alaska. Anthropologists estimate that the entire Indian population north of Mexico was slightly greater than 1,020,000 when the first settlers arrived from Europe. Although Native Americans belonged to one geographic race, their cultures and languages were only marginally similar, and by and large, they had different ways of life. Nomadic migrations required Indians to construct shelters that did not need to be transported, but could be easily erected from the materials found in their new location.
            Eastern Woodland Indian tribes lived in bark-covered wigwams hat were shaped like cones or domes. The frame for the hut was made of young trees firmly driven into the ground, and then bent overhead to tie together with bark fibers or strings of animal hides. Sheets and slabs of bark were attached to the frame to construct the roof and walls, leaving and opening to serve as a door and to allow smoke to escape. The Iroquois in north eastern regions built longhouses that were more spacious than wigwams because five to a dozen families lived under one roof. During the winter, they plastered clay to the poles of the frame to protect the inhabitants from wind and rain.
            Pueblo Indians who lived in the southwest portion of the United States in northern Arizona and New Mexico constructed elaborate housing with several stories and many rooms. Each family unit had only one room, and their ancestors dug shelters in the walls of cliffs and canyons. The ground story of a Pueblo dwelling had no doors or windows in order to prevent enemies from entering. The next level was set back the width of one room, and the row of rooms above it was set back once again, giving their houses the appearance of a terrace. Pueblos used ladders to climb to the upper levels and pulled them in when all family members returned for the night.
            Indians living in deserts used sandstone and clay as construction materials. Those who lived in the valleys of rivers even made bricks of clay with wood chips to add strength and to prevent the clay from cracking. To make roofs, Pueblos tied logs together to make rafters and laid them across the two outside walls. On top of the rafters, layers of tree branches, sticks, grass, and brush created a solid roof to preclude the water from leaking inside. Pueblo dwellings were dark because windows were often not large enough to allow much light.
The word “preclude”  is closest in meaning to
A.include           
B.stop
C.preserve
D.conclude

Các câu hỏi liên quan

Read the following passage  and mark the letter (A, B, C or D) on your answer sheet to indicate the correct answer to each for  the questions. 
      The pain of a migraine headache can virtually disable a person who suffers from it. Millions and millions of people suffer from migraines, although many of them do not even recognize that a migraine is different from a regular headache. A migraine is not at all the same as a normal headache, and it seems to have a very physical cause.
       One symptom of a migraine is a precursor, which is a visual aura before an attack. Yet only about a third of patients actually experience that, and it is therefore not a requirement in the diagnosis. Other symptoms include increased pain when a person moves, nausea, and sensitivity to light and sound. Scientists now believe that migraines are caused, not by abnormal blood vessels as previously believed, but instead by a unique electrical disorder of  brain cells. Physicians used to treat migraines with medicine to constrict blood vessels because of the belief that dilated  blood vessels were the cause.
       The new research has been enhanced by imaging devices that allow scientists to watch patients' brains during an attack. The results show that sufferers have abnormally excitable neurons, or brain nerve cells. Prior to the attack, the neurons suddenly fire off electrical pulses at the back of the brain, which ripple like waves on a lake after a stone hits the water. They ripple across the top and then the back of the brain, ultimately affecting the brain stem where the pain centers are located. The pain then generates possibly from the brain stem itself or from blood vessels inflamed  by the rapidly changing blood flow, or perhaps from both.
       Scientists have experimented by applying a powerful magnet to stimulate the neurons and discovered that some people's brains react differently than others'. When stimulation was applied to the brains of people who had suffered migraines, they saw the initial aura, and some actually suffered migraines. When the same stimulation was applied to the brains of people who had never suffered migraines, they realized no effect and the neurons showed no change.         
 Scientists and doctors continue to work on the research in an attempt to find the perfect treatment. It is considered important to treat migraines because it is believed that prolonged untreated attacks could cause physical changes in the brain leading to chronic pain. 
The author implies that a migraine 
A.is just a strong headache. 
B.can be treated with regular aspirin.   
C.is caused by the same things that cause a headache.   
D.has a specific scientific cause, unlike a headache.