在体内可转换成尼克酸的氨基酸是（） A.亮氨酸 B.蛋氨酸 C.半胱氨酸 D.酪氨酸
题型：单项选择题
问题：
在体内可转换成尼克酸的氨基酸是（）
A.亮氨酸
B.蛋氨酸
C.半胱氨酸
D.酪氨酸
E.色氨酸
题型：单项选择题
第三部分阅读理解(共20小题；每小题2分．满分40分)
阅读下列短文。从每题所给的四个选项(A、B、C和D)中，选出最佳选项，并在答题卡
上将该项涂黑。 ，
On an—airplane，a spacecraft or a man-made satellite，there is usually an installad device called the“biack box ”Made of a special kind of material．it would remain unbroken，even if the entire craft were blown to pieces．The box records some important data,which provide clues as to what changes had occurred before the real thing came along and help to discover the causes of the
disaster．
The black box．Therefore, becomes the last piece of evidence left.More often,it reveal a Schocking fact that many aircrafts met their disasters only beeanse of a simple but fatal mistake
Some hadn’t been supplied with sufficient fuel；others crashed due to a bird flying in their paths.In many cases。the pilot had been tired．In 1986，the famous US space siadttle Challenger exploded
soon after launch, because a screw on it was a bit loose!
An idea thus occurs to me：if a human being was equipped with a similar device,tracking all
the subtle inner Changes that had taken place over time，the results could astonish the world
Newspapers carry no few sueh stories from day to day－cases of graft or bribe-taking(行贿或受贿)，how—innocent maIl was robbed and killed,and so on．A fatal error,committed by a criminal at a particuiar point in his life，may have arisen from a small quarrei or
out of envy．The number of those who were bom evil and deliberately sent themselvas to the“gallows(绞架)”is in fact extremely small．The disappointment towards the last moment of their life is no different from a struggl against an aircraft crash！
Behave properl in small matters and take best care of the soul---this，I’insist,is the message
from that mysterious box planted deep inside human souls
56．The underlianed phrese”a similar device” in Paragraph 3 refers to
A ；the mysterious box inside human souls． B．the causes of the disasters；
C. The fatal mistake of space shuttles． D．the function of the black box.
57．The underlined phrase“a similar device”in Paragraph 3refers to
A：a useful device B.a black box
C. an installed device D．an important instrument
58．According to the text,which ofthe following is NOT true?
A Most ofus were bom kind，but those evil by nature are not in small numbers．
B．Many crashes should have been avoided ifpilots had been careful.
C．Some small errors can even cause a long-lasting regret．
D．~’Even ifthe plane blows up，the black box can still function·.
59．The best title for the text is
A．The Black Box B．The Black Box and Disasters
C． The Black Box ofthe Soul D．The Black Box and Humans
60．The purpose of the author is to
A． warn us of our safety B．tell us to treat others kindly
C． how us his concerns D．remind us of taking good care of our soul