共用题干
The Day a Language Died
When Carlos Westez died at the age of 76,a language died,too.Westez,more commonly known as Red Thunder Cloud,was the last speaker of the Native American language,Catawba.Anyone who wants to hear various songs of the Catawba can contact the Smithsonian Institution in Washington,D.C.,where, back in the 1940s,Red Thunder Cloud recorded a series of songs for future generations.______(46) They are all that is left of the Catawba language.The language that people used to speak is gone forever.
We are all aware of the damage that modern industry can do to the world's ecology（生态）.However, few people are aware of the impact that widely spoken languages have on other languages and ways of life.English has spread all over the world.Chinese,Spanish,Russian,and Hindi have become powerful languages,as well.______(47)When this happens,hundreds of languages that are spoken by only a few people die out.
Scholars believe there are about 6 ,000 languages around the world,but more than half of them could die out within the next 100 years.There are many examples.Araki is a native language of the island of Vanuatu,located in the Pacific Ocean.It is spoken by only a few older adults,so like Catawba,Araki will soon disappear.Many languages of Ethiopia will have the same fate because each one has only a few speakers.______(48)In the Americas,100 languages,each of which has fewer than 300 speakers,also are dying out.
Red Thunder Cloud was one of the first to recognize the threat of language death and to try to do something about it.He was not actually born into the Catawba tribe,and the language was not his mother tongue.______(49)The songs he sang for the Smithsonian Institution helped to make Native American music popular.Now he is gone,and the language is dead.
What does it mean when a language disappears? When a plant or insect or animal species dies,it is easy to understand what we've lost and to appreciate what this means for the balance of the natural world.However,language is only a product of the mind.To be the last remaining speaker of a language,like Red
Thunder Cloud,must be a lonely destiny,almost as strange and terrible as being the last surviving member of a dying species.______(50)
_______(47)
A:Some people might want to try to learn some of these songs by heart.
B:Papua New Guinea is an extremely rich source of different languages,but more than 100 of them are in danger of extinction（灭绝）.
C:However,he was a frequent visitor to the Catawba reservation in South Carolina,where he learned the language.
D:These languages don't have many native speakers.
E:For the rest of us,when a language dies,we lose the possibility of a unique way of seeing and describing the world.
F:As these languages become more powerful,their use as tools of business and culture increases.
共用题干
Learn About Noble Gases（惰性气体）
1 Have you ever ridden on a balloon?Many tourist spots offer balloon rides in order for people to see
the beauty of a place from above.A balloon contains a noble gas called helium（氦）.Formerly,balloons con-
tamned hydrogen but hydrogen is very flammable and dangerous when uncontrolled.Therefore,people shifted
to helium,which is safer. Helium is safe because it has the properties of the noble gases.
2 People once believed that noble gases couldn't chemically react at all.For this reason,they were
called inert gases（惰性气体）.They were also listed under Group 0 in the old periodic table because scien-
tists believed that the gases have zero valence（价）electrons in their outer shell.This was later proven to be
untrue when some noble gas compounds were discovered.
3 The gases are elements,which share similar properties.These properties include being monoatomic,
colorless,odorless,being able to conduct electricity,and having low chemical reactivity.Noble gases
include helium,neon,argon,krypton,xenon and radon.These are all found in Group 18,in the right most
column of the periodic table.If you look at the periodic table,you will notice that these elements are the only
ones which do not have a charge. Helium has the lowest molecular（分子的）weight while radon is the
heaviest.
4 Remember that chemical reactions occur because atoms have valence electrons,which are electrons
in their outer shell.When the outer shell is"unfilled"or the required number of electrons is not yet corn-
plete,the atom is more reactive.Noble gases have a full outer shell,meaning that they have complete elec-
trons in their outer shell.This complete number varies.For instance,the outer shell of helium has 2 valence
electrons while the outer shell of xenon has 8 electrons.Nowadays,there remains to be a few noble gases
because of the low chemical reactivity of these said gases.
5 because of their properties,noble gases have many important applications.They are widely used in
medicine and industries. For instance , liquid helium is used for superconducting magnets（磁体）.These
magnets are very important in physics and medicine.When a doctor suspects that a person's brain has been
damaged,he might request for Magnetic Resonance Imaging(MRI).MRI allows the doctor to"see"the
brain,without operating on the patient.
Paragraph 2 ____________
A:How were Noble Gases Discovered?
B:What is the Periodic Table?
C:What are the Applications of Noble Gases?
D:How were Noble Gases Understood in the Past?
E:What Causes the Low Chemical Reactivity of Noble Gases?
F:What are Noble Gases?
