托福阅读真题及答案

，一类是

fishing

，有

< br>可能被发现的是

fishing

的，它待在冰上，随着冰 漂移

2000mi

也是很

容易滴，所以 在这两个地方发现同一个是很有可能的。

c.

年龄有可能被预估错误了，这个生物到

20

岁以后就没啥变化了，

20

岁和

3 0

岁长得很像的。

科学家认为是

20< /p>

岁，

万一是

25

捏

?

反正就是

年龄预估这事不靠谱。< /p>

综上所述，教授认为，很有可能是同一个物种

2

、有些人认为成绩应该由许多小

assi gnment

的成绩综合，有些

人认为应该

1-2

次大成绩。写出自己的观点，并给出案例和分析。

托福阅读真题及答案

Timberline Vegetation on Mountains

The transition from forest to treeless tundra on a mountain slope is

often

a

dramatic

one.

Within

a

vertical

distance

of

just

a

few

tens

of

meters,

trees

disappear

as

a

life-form

and

are

replaced

by

low

shrubs,

herbs,

and

grasses.

This rapid zone of transition is called the upper timberline or tree line. In

many

semiarid

areas

there

is

also

a

lower

timberline

where

the

forest

passes

into steppe or desert at its lower edge, usually because of a lack of

moisture.

The upper timberline, like the snow line, is highest in the tropics and

lowest in the Polar Regions. It ranges from sea level in the Polar Regions

to

4,500

meters

in the dry

subtropics

and

3,500-4,500

meters

in the

moist

tropics.

Timberline

trees

are

normally

evergreens,

suggesting

that

these

have

some

advantage

over

deciduous

trees

(those

that

lose

their

leaves)

in

the

extreme

environments

of

the

upper

timberline.

There

are

some

areas,

however,

where

broadleaf

deciduous

trees

form

the

timberline.

Species

of

birch,

for

example,

may occur at the timberline in parts of the Himalayas.

At

the

upper

timberline

the

trees

begin

to

become

twisted

and

deformed.

This is particularly true for trees in the middle and upper latitudes, which

tend to attain greater heights on ridges, whereas in the tropics the trees

reach

their greater heights in the valleys. This is because middle- and upper-

latitude timberlines are strongly influenced by the duration and depth of

the

snow cover. As the snow is deeper and lasts longer in the valleys, trees

tend to

attain greater heights on the ridges, even though they are more exposed to

high-velocity winds and poor, thin soils there. In the tropics, the valleys

appear to be more favorable because they are less prone to dry out, they

have

less frost, and they have deeper soils.

There

is

still

no

universally

agreed-on

explanation

for

why

there

should be

such a dramatic cessation of tree growth at the upper timberline. Various

environmental factors may play a role. Too much snow, for example, can

smother

trees,

and

avalanches

and

snow

creep

can

damage

or

destroy

them.

Late-lying snow

reduces the effective growing season to the point where seedlings cannot

establish themselves. Wind velocity also increases with altitude and may

cause

serious stress for trees, as is made evident by the deformed shapes at high

altitudes. Some scientists have proposed that the presence of increasing

levels

of

ultraviolet

light

with

elevation

may

play

a

role,

while

browsing

and

grazing

animals

like

the

ibex

may

be

another

contributing

factor.

Probably

the

most

important environmental factor is temperature, for if the growing season

is too

short and temperatures are too low, tree shoots and buds cannot mature

sufficiently to survive the winter months.

Above

the

tree

line

there

is

a

zone

that

is

generally

called

alpine

tundra.

Immediately

adjacent

to

the

timberline,

the

tundra

consists

of

a

fairly

complete

cover of low-lying shrubs, herbs, and grasses, while higher up the number

and

diversity

of

species

decrease

until

there

is

much

bare

ground

with

occasional

mosses and lichens and some prostrate cushion plants. Some plants can

even

survive

in

favorable

microhabitats

above

the

snow

line.

The

highest

plants in

the world occur at around 6,100 meters on Makalu in the Himalayas. At

this great

height, rocks, warmed by the sun, melt small snowdrifts.

The

most

striking

characteristic

of

the

plants

of

the

alpine

zone

is

their

low

growth

form.

This

enables

them

to

avoid

the

worst

rigors

of

high

winds and

permits

them

to

make

use

of

the

higher

temperatures

immediately

adjacent to the

ground surface. In an area where low temperatures are limiting to life, the

importance

of

the

additional

heat

near

the

surface

is

crucial.

The

low

growth

form

can

also

permit

the

plants

to

take

advantage

of

the

insulation

provided by

a winter snow cover. In the equatorial mountains the low growth form is

less

prevalent.

Paragraph

1:

The

transition

from

forest

to

treeless

tundra

on

a

mountain

slope is often a dramatic one. Within a vertical distance of just a few tens

of

meters,

trees

disappear

as

a

life-form

and

are

replaced

by

low

shrubs,

herbs,

and grasses. This rapid zone of transition is called the upper timberline or

tree line. In many semiarid areas there is also a lower timberline where

the

forest passes into steppe or desert at its lower edge, usually because of a

lack

of moisture.

1. The word “dramatic” in the passage is closest i

n meaning to

○gradual

○complex

○visible

○striking

2. Where is the lower timberline mentioned in paragraph 1 likely to

be

found?

○In an area that has little water

○In an area that has little sunlight

○Above a transit

ion area

○On a mountain that has on upper timberline.

3.

Which of the

following can be inferred

from

paragraph

1 about

both the

upper and lower timberlines?

○Both are treeless zones.

○Both mark forest boundaries.

○Both are surroun

ded by desert areas.

○Both suffer from a lack of moisture.

Paragraph 2: The upper timberline, like the snow line, is highest in

the

tropics and lowest in the Polar Regions. It ranges from sea level in the

Polar

Regions to 4,500 meters in the dry subtropics and 3,500-4,500 meters in

the

moist

tropics.

Timberline trees are normally

evergreens,

suggesting that

these

have some advantage over deciduous trees (those that lose their leaves) in

the

extreme

environments

of

the

upper

timberline.

There

are

some

areas,

however,

where broadleaf deciduous trees form the timberline. Species of birch, for

example, may occur at the timberline in parts of the Himalayas.

4.

Paragraph

2

supports

which

of

the

following

statements

about

deciduous

trees?

○They cannot grow in cold climates.

○They do not exist at the upper timberline.

○They are less likely than evergreens to survive at the upper

timberline.

○They do not require as much moisture as evergreens do.

Paragraph

3:

At

the

upper

timberline

the

trees

begin

to

become

twisted and

deformed.

This

is

particularly

true

for

trees

in

the

middle

and

upper

latitudes,

which tend to attain greater heights on ridges, whereas in the tropics the

trees

reach

their

greater

heights

in

the

valleys.

This

is

because

middle-

and

upper-

latitude timberlines are strongly influenced by the duration and depth of

the

snow cover. As the snow is deeper and lasts longer in the valleys, trees

tend to

attain greater heights on the ridges, even though they are more exposed to

high-velocity winds and poor, thin soils there. In the tropics, the valleys

appear to be more favorable because they are less prone to dry out, they

have

less frost, and they have deeper soils.

5. The word “attain” in the passa

ge is closest in meaning to

○require

○resist

○achieve

○endure

6. The word “they” in the passage refers to

○valleys

○trees

○heights

○ridges

7. The word “prone” in the passage is closest in meaning

to

，

/toefl/

来源：北京新航道托福培训

○adapted

○likely

○difficult

○resistant

8. According to paragraph 3, which of the following is true of trees

in the

middle and upper latitudes?

○Tree growth is negatively affected by the snow cove

r in valleys.

○Tree growth is greater in valleys than on ridges.

○Tree growth on ridges is not affected by high

-velocity winds.

○Tree growth lasts longer in those latitudes than it does in the

tropics.

Paragraph 4

：

There is still no universally agreed-on explanation for

why

there should be such a dramatic cessation of tree growth at the upper

timberline.

Various

environmental

factors

may

play

a

role.

Too

much

snow, for

example, can smother trees, and avalanches and snow creep can damage

or destroy

them. Late-lying snow reduces the effective growing season to the point

where

seedlings cannot establish themselves. Wind velocity also increases with

altitude and may cause serious stress for trees, as is made evident by the

deformed shapes at high altitudes. Some scientists have proposed that the

presence of increasing levels of ultraviolet light with elevation may play a

role, while browsing and grazing animals like the ibex may be another

contributing factor. Probably the most important environmental factor is

temperature, for if the growing season is too short and temperatures are

too

low, tree shoots and buds cannot mature sufficiently to survive the winter

months.

9.

Which

of

the

sentences

below

best

express

the

essential

information in

the

highlighted

sentence

in

the

passage?

In

correct

choices

change

the

meaning

in important ways or leave out essential information.

○Because

of

their

deformed

shapes

at

high

altitudes,

trees

are

not

likely

to be seriously harmed by the strong winds typical of those altitudes.

○As altitude incr

eases, the velocity of winds increase, leading to a

serious decrease in the number of trees found at high altitudes.

○The

deformed

shapes

of

trees

at

high

altitudes

show

that

wind

velocity,

which increase with altitude, can cause serious hardship for trees.

○Increased

wind

velocity

at

high

altitudes

deforms

the

shapes

of

trees, and

this may cause serious stress for trees.

10.

In

paragraph

4,

what

is

the

author

’

s

main

purpose

in

the

discussion of

the dramatic cessation of tree growth at the upper timberline?

○To argue that none of several environment factors that are believed

to

contribute to that phenomenon do in fact play a role in causing it.

○To

argue

in

support

of

one

particular

explanation

of

that

phenomenon

against several competing explanations

○To

explain

why

the

primary

environmental

factor

responsible

for

that

phenomenon has not yet been identified

○To present several environmental factors that may contribute to a

satisfactory explanation of that phenomenon

Paragraph

6:

The

most

striking

characteristic

of

the

plants

of

the

alpine

zone

is

their

low

growth

form.

This

enables

them

to

avoid

the

worst

rigors of

high

winds

and

permits

them

to

make

use

of

the

higher

temperatures

immediately

adjacent

to

the

ground

surface.

In

an

area

where

low

temperatures

are

limiting

to life, the importance of the additional heat near the surface is crucial.

The

low

growth

form

can

also

permit

the

plants

to

take

advantage

of

the

insulation

provided

by

a

winter

snow

cover.

In

the

equatorial

mountains

the

low

growth form

is less prevalent.

11. The word “prevalent” in the passage is closest in meaning to

○predictable

○widespread

○successful

○developed

12. According to paragraph 6, all of the following statements are true

of

plants in the alpine zone EXCEPT:

○Because they are low, they are less exposed to strong winds.

○Because

they

are

low,

the

winter

snow

cover

gives

them

more

protection

from the extreme cold.

○In

the

equatoria

l

mountains,

they

tend

to

be

lower

than

in

mountains

elsewhere.

○Their

low

growth

form

keeps

them

closer

to

the

ground,

where

there is more

heat than further up.

Paragraph

5:

Above

the

tree

line

there

is

a

zone

that

is

generally

called

alpine

tundra.

█Immediately

adjacent

to

the

timberline,

the

tundra

consists of a

fairly

complete

cover

of

low- lying

shrubs,

herbs,

and

grasses,

while

higher up

the

number

and

diversity

of

species

decrease

until

there

is

much

bare

ground

with

occasional

mosses

and

lichens

and

some

prostrate

cushion

plants.

█Some

plants can even survive in favorable microhabitats above the snow line.

The

highest plants in the world occur at around 6,100 meters on Makalu in the

Himalayas. █At this great height, rocks, warmed by

the sun, melt small

snowdrifts. █