重组热点（hot spots of recombination）

突变热点(hot spots of mutation)

Critics of hot spots hold the opinion that ________.

A) hot spots are always as important as cold spots

B) it is unwise to invest largely in hot spots

C) governments should choose the best time to invest in hot spots

D) the hot-spot approach is a misleading strategy from the very beginning

According to Dr. Norman Myers, _________.

A) protecting and investing in hot spots can save species from extinction

B) conservation efforts should not center on hot spots

C) governments should invest most in cold spots

D) the hot-spot approach now is not as good as it was in the past

According to the passage, which one below is not the hot spots main function？

A．Measuring instrument of the continent movement.

B．A frame. of reference of the passage of plates.

C．To initiate the formation of new ocean.

D．To explain the mutability of the continents.

The main idea of the passage is ______.

A．the development of sonar technology

B．how to avoid ship and whale collision

C．the hot spots for whale collision

D．the giant creature of the sea

The author believes that_____________.

A.the motion of the plates corresponds to thar of the earth's interior

B.the geological theory about drifting plates has been proved to be true

C.the hot spots and the plates move slowly in opposite directions

D.the movement of hot spots proves the continents are moving apart

A) a third of all plants B) many major animal groups living in cold spots

C) rich biological diversity D) many rare species living in cold spots

nown to geologists as hot spots, unlike most of the world's volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth's surface; on the contrary, many of them lie deep in the interior of a plate. Most of the hot spots move only slowly, and in some cases the movement of the plates past them has left trails of dead volcanoes. The hot spots and their volcanic trails are milestones that mark the passage of the plates.

That the plates are moving is now beyond dispute. Africa and South America, for example, are moving away from each other as new material is injected into the sea floor between them. The complementary coastlines and certain geological features that seem to span the ocean are reminders of where the two continents were once joined. The relative motion of the plates carrying these continents has been constructed in detail, but the motion of one plate with respect to another cannot readily be translated into motion with respect to the earth's interior. It is not possible to determine whether both continents are moving in opposite directions or whether one continent is stationary and the other is drifting away from it. Hot spots, anchored in the deeper layers of the earth, provide the measuring instruments needed to resolve the question. From an analysis of the hot spot population it appears that the African plate is stationary and that it has not moved during the past 30 mil lion years.

The significance of hot spots is not confined to their role as a frame. of reference. It now appears that they also have an important influence on the geophysical processes that propel the plates across the globe. When a continental plate comes to rest over a hot spot, the material rising from deeper layer creates a broad dome. As the dome grows, it develops deed fissures (cracks); in at least a few cases the continent may break entirely along some of these fissures, so that the hot spot initiates the formation of a new ocean. Thus just as earlier theories have explained the mobility of the continents, so hot spots may explain their mutability (inconstancy).

The author believes that ______.

A．the motion of the plates corresponds to that of the earth's interior

B．the geological theory about drifting plates has been proved to be truse

C．the hot spots and the plates move slowly in opposite directions

D．the movement of hot spots proves the continents are moving apart

The passage is mainly about ______.

A．the features of volcanic activities

B．the importance of the theory about drifting plates

C．the significance of hot spots in geophysical studies

D．the process of the formation of volcanoes

zona. For hot temperatures but lots of rain and thunderstorms, try Miami, Florida. If you want average temperatures and rainfall, St. Louis, Missouri, is the spot. Or if you' re a cold weather fan, head to Fairbanks, Alaska. Its winters are very cold with little precipitation. Each of these cities has a certain type of weather. The average weather for a place over many years is called climate, and in no two places in (he world is it exactly the same. How can this be？

Many things in nature, such as sunshine, temperature, and precipitation, affect climate. Nearness to mountain, oceans, and large lakes affects it loo. Another factor is altitude, or height above sea level. Air cools as altitude increases. So a city at a higher altitude may be colder than one at a lower altitude. Finally, winds affect climate. They move heat and moisture between the oceans and continents. Winds keep the tropics from overheating. They keep the polar regions from getting overly cold.

Climate changes over long periods of time. Some scientists think, for example, that the earth' s climate changed at the time of the dinosaurs. They think the dinosaurs died because of the change. What causes a climate to change？ One possible cause may be changes in the sun. Sunspots, for example, are cool, dark spots that form. on the sun. Sunspots may decrease precipitation on the earth and cause unusually dry periods. Changes in the atmosphere may change climate too. Volcanic eruptions, for instance, release solid particles into the air. These particles may form. a cloud that blocks out the sun ' s heat. Human activity is another cause of climate change. Air pollution and the reduction of forest cover may have long-term effects on climate.

This passage is concerned with things that affect______.

A．precipitation

B．climate

C．altitude

D．sunspots