In cold, damp weather, the buildup of ice on airplane wings can pose significant aerodynamic problems. Which of the following effects would you expect?A.As ice builds up on the top of the wing, drag increases.B.As ice builds up on the top of the wing, lif

共用题干
Rainmaking
1 The idea of rainmaking is almost as old as man,but it was not until 1946 that man succeeded in making rain.In ancient times,rainmakers had claimed to bring rain by many methods:dancing.singing-Kiiiing animals t including humans).
2 For a long time,men have understood where rain comes from.Water from the surface of oceans and lakes becomes part of the air,where it forms clouds from which rain falls.But exactly what starts the formation of raindrops was not known until quite recently.A man named John Aitken proved that drops of water gather around tiny bits of dust or other matter.The centers of the drops are so small that the human eye cannot see them.Without such centers,it seems raindrops do not form.
3 During World War Ⅱ,Dr.Irving Langmir,and his assistant Schaefer,were hired by the General Electric Company to study how and why ice forms on the wings of airplanes.They went to a mountain in New Hampshire,where snowstorms are common and cold winds blow.They were surprised to find that often the temperature of the clouds surrounding them was far below the freezing point,and yet ice did not form in the clouds.
4 After the War,Schaefer experimented with a machine that created cold,moist air similar to the air found in clouds.To imitate the moist air of a cloud,Schaefer would breathe into the machine.Then he would drop into the freezer a bit of powder,sugar,or some other substance.For weeks and months he tried everything he could imagine.Nothing happened.No crystals of ice were formed.None of the substances would serve as the center of a snow crystal or raindrops.
5 One July morning,Schaefer was dropping in bits of various substances and watching the unsuccessful results.Finally,a friend suggested that they go to eat lunch and Schaefer went with him.As usual,he left the cover of the freezer up,since cold air sinks and would not escape from the box.
6 Returning from lunch,Schaefer found that the temperature of the freezer had risen to a point higher than that required for ice crystals to remain solid.There were two choices now.He could close the cover and wait for the freezer itself to lower the air temperature,or he could make the process occur faster by adding dry ice-a gas in solid form that is very,very cold.He chose the latter plan.As he dropped the steaming white dry ice into the freezer,he happened to breathe out a large amount of air.And there,before his eyes,it happened!He had made ice crystals,not by adding centers to the moisture,but by cooling the breath so much that the liquid had to form crystals!Then he began to blow his breath into the freezer and drop large pieces of dry ice through it to create crystals which became a tiny snowstorm falling slowly to the floor of his laboratory.
7 After planning carefully,Schaefer made an experiment by dropping dry ice from his plane to the clouds below him.As was expected,snow formed and fell from the bottom of the cloud.Schaefer succeeded.He made history.

Schaefer found a way of how to make ice crystals______.
A:imaginatively
B:recently
C:carefully
D:unscientifically
E:accidentally
F:satisfactorily

You should have put the milk into the ice box, I expect it ____undrinkable by now.

A.became
B.had become
C.has become
D.becomes

资料：A high-precision NASA radar instrument left a NASA airport in Southern California for Iceland on January 28 to create detailed maps of how glaciers move in the dead of winter. This will help scientists around the world better understand some of the most basic processes involved in melting glaciers, which are major contributors to rising sea levels.
NASA used the same airborne instrument in June 2012 to map the summer flows of two Icelandic ice caps. The ice caps — large areas of permanent snow and ice cover — encompass multiple glaciers flowing in different directions and at different speeds. By mapping the same ice caps now, in winter, when the surface remains frozen all day, and then comparing the winter and summer velocities, the researchers will be able to isolate the effects of melt water.
Above is a view of a small part of the Hofsjkull ice cap, which encompasses several glaciers. The fan at upper left is part of a glacier called Mlaj?kull.
For more on the research, see this NASA press release.

How can the scientists figure out the effects of melting water?

A.By melting the frozen iceberg in winter.
B.By observing the snow's moving directions.
C.By isolating ice from water in sunlines.
D.By comparing the glaciers moving speeds.

共用题干
Rainmaking

1 The idea of rainmaking is almost as old as man,but it was not until 1946 that man succeeded in
making rain.In ancient times,rainmakers had claimed to bring rain by many methods:dancing,singing,
killing animals(including humans).
2 For a long time,men have understood where rain comes from.Water from the surface of oceans and
lakes becomes part of the air,where it forms clouds from which rain falls.But exactly what starts the forma-
tion of raindrops was not known until quite recently.A man named John Aitken proved that drops of water
gather around tiny bits of dust or other matter. The centers of the drops are so small that the human eye can-
not see them.Without such centers,it seems raindrops do not form.
3 During World War Ⅱ,Dr. Irving Langmir,and his assistant Schaefer,were hired by the General
Electric Company to study how and why ice forms on the wings of airplanes.They went to a mountain in New
Hampshire,where snowstorms are common and cold winds blow. They were surprised to find that often the
temperature of the clouds surrounding them was far below the freezing point,and yet ice did not form in the
clouds.
4 After the War,Schaefer experimented with a machine that created cold,moist air similar to the air
found in clouds.To imitate the moist air of a cloud.Schaefer would breathe into the machine.Then he
would drop into the freezer a bit of powder,sugar,or some other substance.For weeks and months he tried
everything he could imagine.Nothing happened.No crystals of ice were formed.None of the substances
would serve as the center of a snow crystal or raindrops.
5 One July morning,Schaefer was dropping in bits of various substances and watching the unsuccessful
results.Finally,a friend suggested that they go to eat lunch and Schaefer went with him.As usual,he left
the cover of the freezer up,since cold air sinks and would not escape from the box.
6 Returning from lunch,Schaefer found that the temperature of the freezer had risen to a point higher
than that required for ice crystals to remain solid.There were two choices now.He could close the cover and
wait for the freezer itself to lower the air temperature,or he could make the process occur faster by adding dry
ice a gas in solid form that is very,very cold.He chose the latter plan.As he dropped the steaming white
dry ice into the freezer,he happened to breathe out a large amount of air. And there,before his eyes,it
happened ! He had made ice crystals,not by adding centers to the moisture,but by cooling the breath so
much that the liquid had to form crystals!Then he began to blow his breath into the freezer and drop large
pieces of dry ice through it to create crystals which became a tiny snowstorm falling slowly to the floor of his
laboratory.
7 After planning carefully,Schaefer made an experiment by dropping dry ice from his plane to the
clouds below him.As was expected,snow formed and fell from the bottom of the cloud.Schaefer succeeded.
He made history.

Schaefer found a way of how to make ice crystals_________.
A:imaginatively
B:recently
C:carefully
D:unscientifically
E:accidentally
F:satisfactorily