It was clear that he knew nothing about how to repair cars. A） obvious B） aware C） average D） dim

Avalanche and Its Safety

    An avalanche is a sudden and rapid flow of snow， often mixed with air and water， down a mountainside. Avalanches are ____51____ the biggest dangers in the mountains for both life and property.

    All avalanches are caused by an over-burden of material， typically snowpack， that is too massive and unstable for the slope ____52____ supports it. Determining the critical load， the amount of over-burden which is ____53____ to cause an avalanche， is a complex task ____54____ the evaluation of a number of factors.

    Terrain slopes flatter than 25 degrees or steeper than 60 degrees typically have a low ____55____ of avalanche. Snow does not ____56____ significantly on steep slopes； also， snow does not ____57____ easily on fiat slopes. Human-triggered avalanches have the greatest incidence when the snow‘s angle of rest is ____58____ 35 and 45 degrees； the critical angle， the angle ____59____ which the human incidence of avalanches is greatest， is 38 degrees. The rule of thumb is： A slope that is flat enough to hold snow but steep enough to ski has the potential to generate an avalanche， regardless of the angle. Additionally， avalanche risk increases with ____60____； that is， the more a slope is disturbed by skiers， the more likely it is that an avalanche will occur.

    Due to the complexity of the subject， winter travelling in the backcountry is never 100% safe. Good avalanche safety is a continuous ____61____， including route selection and examination to the snowpack， weather ____62____， and human factors. Several well-known good habits can also ____63____ the risk. If local authorities issue avalanche risk reports， they should be considered and all warnings should be paid ____64____ to. Never follow in the tracks of others without your own evaluations； snow conditions are almost certain to have changed since they were made. Observe the terrain and note obvious avalanche paths where plants are ____65____ or damaged. Avoid traveling below others who might trigger an avalanche.

    51 A among B of C to D in

    52 A when B that C who D whose

    53 A mostly B likely C clearly D surely

    54 A about B include C involving D contain

    55 A weight B form C risk D work

    56 A fall B flow C roll D gather

    57 A fall B flow C roll D gather

    58 A among B between C with D for

    59 A at B of C in D on

    60 A use B time C snow D rain

    61 A journey B trip C fact D process

    62 A conditions B reports C forecast D event

    63 A increase B reduce C improve D remove

    64 A price B effort C attention D money

    65 A missing B grown C big D fresh

The phrasal verb “fatten up” in paragraph 6 could be best replaced by

    A invent

    B rewrite

    C polish.

    D complete

What do student leaders need to carry an activity through to a successful end？

    A Passion

    B Money

    C Power

    D Fame

American students join campus organizations mostly for

    A making a difference

    B gaining experience

    C building friendship

    D improving their resumes

An extracurricular activity like raising a fund of $300，000 is risky because most student leaders

    A are lazy

    B are stupid

    C are not rich enough

    D will not take an interest in it

Which of the following is closest in meaning to the title？

    A Human hair may help detectives to solve crimes.

    B Animal hair may help detectives to solve crimes.

    C Human hair‘s features.

    D Most detectives are hair specialists.

James R. Ehleringer tried to find out

    A if tap water contains unique proportions of isotopes of hydrogen and oxygen.

    B if it is possible to collect hair samples across the country.

    C if our bodies break water down into its parts.

    D if the composition of hair can indicate exactly where people are from.

Which of the following about tap water is NOT correct？

    A Tap water reflects the concentrations of hydrogen and oxygen isotopes in different regions.

    B Tap water contains unique proportions of isotopes of hydrogen and oxygen.

    C Tap water is a kind of soft drink in the United States

    D Tap water is used to cook food.

In the second paragraph， the underlined sentence means “if we______.”

    A pick any two persons

    B take out two different persons

    C choose two persons who are relative

    D choose two persons with different intelligence

If a child is born with low intelligence， he can______.

    A become a genius

    B still become a genius if he should be given special education

    C reach his intelligence limits in rich surroundings

    D not reach his intelligence in his life