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0308
托福試題
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55minutes
)
Question 1-11
If
food
is
allowed
to
stand
for
some
time,
it
putrefies .When the putrefied material
is
examined
microscopically
,it
is
found
to
be
teeming with bacteria. Where do these
bacteria
come
from
,
since
they
are
not
seen
in
fresh food? Even until the mid-nineteenth
century,
many
people
believed
that
such
microorganisms originated by spontaneous
(5
)
generation
,a
hypothetical
process
by
which
living organisms develop from nonliving
matter.
The
most
powerful
opponent
of
the
theory
of
spontaneous
generation
was
the
French
chemist
and
microbiologist
Louis
Pasteur(1822-1895).Pasteur
showed that structures
present
in
air
closely
resemble
the
microorganisms
seen in putrefying materials .He did
(10)
this
by
passing
air
through
guncotton
filters,
the fibers of which stop solid particles. After
the guncotton was dissolved in a mixture of alcohol
and ether, the particles that it had
trapped
fell
to
the
bottom
of
the
liquid
and
were
examined on a microscope slide .Pasteur
found that in ordinary air these exists a variety of
solid structures ranging in size from
0.01
mm
to
more
than
1.0
mm .Many
of
these
bodies
resembled the reproductive
(15)
structures of common molds, single-celled animals,
and various other microbial cells .
As
many
as
20
to
30
of
them
were
found
in
fifteen