三个电阻之比为R1:R2:R3=1:2:5,将这三个电阻并联,则通过这三支路的电流强度I1:I2:I3之比为() A . 1:2:5 B . 5:2:1 C . 10:5:2 D . 2:5:10 答案:CA new study shows one of the largest glaciers(冰川) in Greenland is becoming smaller and speeding to the
sea faster than scientists expected. If it continues, Greenland itself could
become much smaller during this century and global seas could rise as much as 3
feet.
The rates of change that we’re noticing are much
higher than expected. If these rates continue, it is not likely that Greenland
could shrink by several tens of percent this century. However, it’s not known
how quickly this coastal response of the Greenland ice sheet melting will have
an effect on the vast inland ice.
Greenland is the world’s largest island, covering area
more than three times the size of Texas. Some 81 percent of it is covered by
ice, and there are many glaciers. Glaciers are like slow-moving rivers of ice.
Where a glacier meets the sea, its weight keeps it firmly resting on the
bottom. A glacier’s front is the point where the water is deep enough that the
glacier floats.
Since the 1970s, the front of Helheim stayed in the
same place. Then it began melting rapidly, moving back 4.5 miles from 2001
through this past summer. It has also grown thinner, from top to bottom, by
more than 130 feet since 2001. And over these past years, its trip to the sea
has sped up from about 70 feet per day to nearly 110.
The melting is driven by a warmer climate.
Temperatures in Greenland have risen more than five degrees Fahrenheit(华氏温度) in the last ten years. Since most of Greenland’s ice
is on land, seas will rise as the ice melts. If all Greenland’s ice sheet
melted, oceans would be 15-20 feet higher. Nobody expects that to happen any
time soon.
1.What can we know about the glaciers according to the
passage?
A.Glaciers only
lie in Greenland.
B.Water in
glaciers is more than sea water.
C.Glaciers
sometimes float on the water.
D.Glaciers can
increase the water level of lakes.
2.According to the passage, we know that Greenland
___________.
A.belongs to
Canada
B.is the
largest island in North America
C.is all
covered with glaciers
D.is sinking
under the sea level
3.Which of the following may be the result of the
disappearing of Greenland glaciers?
A.The climate of
the world will be warmer.
B.The glaciers
in other areas will be bigger.
C.It will be
easy for explorers to visit the island.
D.Some coastal
cities may be under the sea.