1998年5月托福考试阅读理解全真试题
Helium is created in stars. In fact， nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However， the amount of helium that could have been produced in this manner can be calculated，and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significantly greater. Consequently， if the universe is somewhat more than 25 percent helium now， then it must have been about 25 percent helium at a time near the beginning……
However， when the universe was less than one minute old， no helium could have existed. Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time，the universe had cooled sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formation of helium went on for only a relatively short time. By the time the universe was a few minutes old， helium production had effectively ceased.
12.What does the passage mainly explain？
（A）How stars produce energy
（B）The difference between helium and hydrogen
（C）When most of the helium in the universe was formed
（D）Why hydrogen is abundant
13.According to the passage， helium is
（A） the second-most abundant element in the universe
（B） difficult to detect
（C） the oldest element in the universe
（D） the most prevalent element in quasars
14.The word "constituents" in line 9 is closest in meaning to
（A） relatives
（B） causes
（C）components
（D） targets
15.Why does the author mention "cosmic rays t in line 10？
（A）As part of a list of things containing helium
（B）As an example of an unsolved astronomical puzzle
（C） To explain how the universe began
（D） To explain the abundance of hydrogen in the universe
16.The word "vary" in line 14 is closest ill meaning to
（A） mean
（B） stretch
（C） change
（D） include
17.The creation of helium within stars
（A） cannot be measured
（B） produces energy
（C） produces hydrogen as a by-product
（D） causes helium to be much more abundant In old stars than In young star：
18. The word "calculated" in line 20 is closest in meaning to
（A） ignored
（B） converted
（C） increased
（D） determined
19.Most of the helium in the universe was formed
（A） in interstellar space
（B） in a very short time
（C）during the first minute of the universe s existence
（D） before most of the hydrogen
20.The word "ceased" in line 35 is closest in meaning to
（A）extended
（B）performed
（C）taken hold
（D）stopped
Questions 21-30
In colonial America， people generally covered their beds with decorative quilts resembling those of the lands from which the quitters had come. Wealthy and socially prominent settlers made quilts of the English type， cut from large lengths of cloth of the same color and texture rather than stitched together from smaller pieces. They mad these until the advent of the Revolutionary War in I 775， when everything English came to be frowned upon.
Among the whole-cloth quilts made by these wealthy settlers during the early period are those now called linsey- woolseys. This term was usually applied to a fabric of wool and linen used In heavy clothing and quilted petticoats worn in the wintertime. Despite the name， linsey-woolsey bedcovers did not often contain linen. Rather， they were made of a top layer of woolen or glazed worsted wool fabric， consisting of smooth， compact yarn from long wool fiber dyed dark blue，green， or brown with a bottom layer of a coarser woolen material，either natural or a shade of yellow. The filling was a soft layer of wool which had been cleaned and separated and the three layers were held together with decorative stitching done with homespun linen thread. Later， cotton thread was used for this purpose. The design of the stitching was often a simple one composed of interlocking circles or crossed diagonal lines giving a diamond pattern.
This type of heavy， warm， quilted bedcover was so large that it hung to the floor. The corners are cut out at the foot of the cover so that the quilt fit snugly around the tall four-poster，beds of the 1700 s， which differed from those of today in that they were shorter and wider； they were short because people slept in a semi-sitting position with many bolsters or pillows，and wide， because each bed often slept three or more. The linsey-woolsey covering was found in the colder regions of the country because of the warmth it afforded. There was no central heating and most bedrooms did not have fireplaces.