9．Astronauts in space may suffer motion sickness，muscle loss，tiredness and bone loss due to low or zero gravity and weightlessness．But scientists at the University of Delaware are experimenting with little worms to better understand how space travel affects astronauts．
The millimeter-long worm，called C．elegans，is often used in medical studies because its life is only about two weeks long．Seventy percent of its DNA is the same as human DNA．
Chandran Sabanayagam，a scientist with the University of Delaware，built a microgravity simulator（模擬器）to test how C．elegans would perform in the actual zero gravity of space．
Scientists use a computer to watch the worms as they constantly turn over the simulator．The computer shows the worms as they would look under a microscope．Mr．Sabanayagam says the worms turn around and around in the simulator for about one week before they take them out，looking for changes in the worms'epigenome．The epigenome are chemical markers that relate to microgravity and that tell the DNA in the cells how to perform．They can be changed by the environment．And those changes pass from one generation to the next．
"When the worms are in microgravity environment some epigenomic marks remain even when we put it back into normal ground conditions．So its offspring（后代）keeps this epigenomic memory of the parents'microgravity environment．"
The information gathered suggests that the epigenomic marks appear during the early part of a worm's life．Mr．Sabanayagam says identifying epigenomic marks is important for human studies in the future．
Mr．Sabanayagam thinks scientists can find genes（基因）in the human genome（基因組）similar to those in the worms that responded to microgravity．He says scientists could possibly observe those genes closely when astronauts travel in space．
Chandran Sabanayagam expects C．elegans to visit the International Space Station within two years．He hopes information gathered from the worm studies can be used to develop simple，low-cost and quick tests to measure an astronaut's health．
72．What is the purpose of the research？A
A．To seek a way to solve astronauts'healthy problems resulting from weightlessness．
B．To produce medicines from the C．elegans DNA to prevent astronauts from diseases．
C．To see how much similar the C．elegans DNA is to that of human．
D．To prove the practicability of taking the C．elegans to the outer space．
73．What does the underlined word"They"in the paragraph 4refer to？C
A．Scientists．
B．The worms．
C．The epigenome．
D．Astronauts．
74．What happens to the worms during the experiment？B
A．They are put under a microscope and turned around and around．
B．There are some changes in their epigenome with the microgravity environment．
C．Some of them can't adjust to normal ground conditions after the experiment．
D．Chemical markers in them have changed so that their DNA can't perform well．
75．According to the passage，scientistsB．
A．a(chǎn)re having difficulties in identifying epigenomic marks in human genes
B．a(chǎn)re still on the way to finding human genes that respond to microgravity
C．have sent C．elegans to the International Space Station for the experiment
D．believe using the worms to measure an astronaut's health is costly and quick．
分析 本文屬于說明文閱讀，作者通過這篇文章主要向我們描述了德拉瓦大學(xué)的科學(xué)家們正在試驗小蟲子，以便更好地理解太空旅行對宇航員的影響
解答 72．A．推理判斷題．根據(jù)第一段He hopes information gathered from the worm studies can be used to develop simple，low-cost and quick tests to measure an astronaut's health可知研究的目的是為了尋求失重對于宇航員的健康產(chǎn)生的問題的解決的途徑；故選A．
73．C．詞義猜測題．根據(jù)文章The epigenome are chemical markers that relate to microgravity and that tell the DNA in the cells how to perform．They can be changed by the environment可知基因組可以隨著環(huán)境做出改變，指的是表觀基因組；故選C．
74．B．推理判斷題．根據(jù)文章The information gathered suggests that the epigenomic marks appear during the early part of a worm's life．Mr．Sabanayagam says identifying epigenomic marks is important for human studies in the future可知實驗過程中蠕蟲有與微重力環(huán)境的表觀基因組發(fā)生一些變化；故選B．
75．B．推理判斷題．根據(jù)文章The information gathered suggests that the epigenomic marks appear during the early part of a worm's life．Mr．Sabanayagam says identifying epigenomic marks is important for human studies in the future可知科學(xué)家們還在探索如何將人類基因在微重力方面做一些改變；故選B．
點評 考察學(xué)生的細(xì)節(jié)理解和推理判斷能力，做細(xì)節(jié)理解題時一定要找到文章中的原句，和題干進(jìn)行比較，再做出正確的選擇．在做推理判斷題不要以個人的主觀想象代替文章的事實，要根據(jù)文章事實進(jìn)行合乎邏輯的推理判斷．
