Lichens can be spectacular for anyone
who cares to look, but few people take the trouble. Often modestly colored, and
seemingly two-dimensional as they cling to whatever surface they find, they grow
in background - as though designed to be ignored. Yet they hold a special
fascination for botanists, partly because they present mysteries still to be
solved and partly because they do so many things so well.
No
casual observer ’of a lichen would ever suspect that it was a composite of
interacting life forms. This seemingly uncomplicated lichen is actually composed
of a fungus and a colony of algae (or blue-green algae, which some scientists
now consider to be bacteria). A few species even include all three of these
diverse forms of life. A complete lichen is strikingly different from its
separated partners in both appearance and
A. a fungus
B. algae
C. a beetle
D. bacteria
更多"{{B}}TEXT D{{/B}}
Liche"的相关试题:
[单项选择]{{B}}TEXT D{{/B}}
Lichens can be spectacular for anyone
who cares to look, but few people take the trouble. Often modestly colored, and
seemingly two-dimensional as they cling to whatever surface they find, they grow
in background - as though designed to be ignored. Yet they hold a special
fascination for botanists, partly because they present mysteries still to be
solved and partly because they do so many things so well.
No
casual observer ’of a lichen would ever suspect that it was a composite of
interacting life forms. This seemingly uncomplicated lichen is actually composed
of a fungus and a colony of algae (or blue-green algae, which some scientists
now consider to be bacteria). A few species even include all three of these
diverse forms of life. A complete lichen is strikingly different from its
separated partners in both appearance and
A. not totally understood by botanists
B. troublesome to collect for the purposes of study
C. uncomplicated in their internal structure
D. not easily noticed by observers
[单项选择] {{B}}TEXT D{{/B}} Can electricity cause
cancer In a society that literally runs on electric power, the very idea seems
preposterous. But for more than a decade, a growing band of scientists and
journalists has pointed to studies that seem to link exposure to electromagnetic
fields with increased risk of leukemia and other malignancies. The implications
are unsettling, to say the least, since everyone comes into contact with such
fields, which are generated by everything electrical, from power lines and
antennas to personal computers and micro-wave ovens. Because evidence on the
subject is inconclusive and often contradictory, it has been hard to decide
whether concern about the health effects of electricity is legitimate—or the
worst kind of paranoia. Now the alarmists have gained some
qualified support from the U. S. Environmental Protection Agency. In the
executive summary of a new scientific review, released in draft form A. studies on the cause of cancer B. controversial view-points in the cause of cancer C. the relationship between electricity and cancer D. different ideas about the effect of electricity on caner
[单项选择] {{B}}TEXT D{{/B}}
What impact can mobile phones have on
their users’ health Many people worry about the supposed ill effects caused by
radiation from handsets and base stations, despite the lack of credible evidence
of any harm. But evidence for the beneficial effects of mobile phones on health
is rather more abundant. Indeed, a systematic review carried out by Rifat Atun
and his colleagues at Imperial College, London, rounds up 150 examples of the
use of text-messaging in the delivery of health care. These uses fall into three
categories: efficiency gains; public-health gains; and direct benefits to
patients by incorporating text-messaging into treatment regimes. The study,
funded by Vodafone, the world’s largest mobile operator, was published this
week.
Using texting to boost efficiency is not rocket science,
but big
A. That cell phones are harmful to people’s health is unconvincing.
B. Cell phones can bring more benefits to people than harm.
C. People won’t worry about the harm cell phones do any longer.
D. There are only three types of benefits cell phones bring us.
[单项选择] {{B}}TEXT C{{/B}}
Can computers reason Reasoning
requires the individual to take a given set of facts and draw correct
conclusions. Unfortunately, errors frequently occur, and we are not talking
about simple carelessness as occurs when two numbers are incorrectly added, nor
do we mean errors resulting from simple forgetfulness. Rather, we have in mind
errors of a logic nature--those resulting from faulty reasoning. Now, or at
least soon, computers will be capable of error-free logical reasoning in a
variety of areas. The key to avoiding errors is to use a computer program that
relies on the last two decades’ research in the field of automated theorem
proving. AURA (Automated Reasoning Assistant) is the program that best
exemplifies this use of the computer.
AURA solves a problem by
drawing conclusions from a given set
A. they have an indefinite life span.
B. they cost little to reproduce.
C. many copies can be made available.
D. they are self-analytical.
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