根据文章，从下框A-F选项中选出能概括每一段主题的最佳选项，选择中有一项为多余。

The year is 2094. It has been announced that a comet is heading towards the Earth. Most of it will miss our planet, but two pieces will probably hit the southern half of the Earth.

On 17 July, a piece four kilometers wide enters the Earth’s atmosphere with a massive explosion. About half of the piece is destroyed, but the remaining part hits the South Atlantic at 200 times the speed of sound. The sea boils and a huge hole is made in the sea bed. Huge waves are created and spread outwards from the hole. The wall of water, a kilometer high, rushes towards southern Africa at 800 kilometers an hour. Cities on the African coast are totally destroyed and millions of people drowned.

Before the waves reach South America, the second piece of the comet lands in Argentina. Earthquakes and volcanoes are set off in the Andes Mountains. The shock waves move north into California and all around the Pacific Ocean. The cities of Los Angeles, San Francisco and Tokyo are completely destroyed by earthquakes. Millions of people in the southern half of the Earth are already dead, but the north won’t escape for long. Because of the explosions, the sun is hidden by clouds of dust, temperatures around the world fall to almost zero. Crops are ruined. The sun won’t be seen again for many years. Wars break out as countries fight for food. A year later, no more than 10 million people remain alive.

Could it really happen? In fact, it has already happened more than once in the history of the Earth. The dinosaurs were on the Earth for over 160 million years. Then 65 million years ago they suddenly disappeared. Many scientists believe that the Earth was hit by a piece of object in space. The dinosaurs couldn’t live through the cold climate that followed and they died out. Will we meet the same end?

1.What is mainly described in the passage?

A. A historic discovery.           B. An event of imagination.

C. A research on space.           D. A scientific adventure.

2.When the first piece hits the South Atlantic, it causes      .

A. an earthquake                B. damages to cities

C. an Earth explosion            D. huge waves

3.Why can’t the northern half of the earth escape for long?

A. Because the land is covered with water.

B. Because the light and heat from the sun can not reach the Earth.

C. Because people there can not live at the temperature of zero.

D. Because wars break out among countries.

4.By giving the example of dinosaurs, the author tries to prove      .

A. animals could not live in the cold climate

B. what happened 65 million years ago was an invented story

C. the human beings will die out in 2094

D. the Earth could be hit by other objects in space

It is high time for us to take measures to protect these old traditions and customs before they _____.

Elephants would ______ if men were allowed to shoot as many as they wished.

A. die down    B. die out       C. die away    D. die off

With only about 1, 000 pandas left in the world, China is desperately trying to clone(克隆) the animal and save the endangered species. That’s a move similar to what  Texas A & M University researchers have been undertaking for the past five years in a project called “Noah’s Ark”.
Noah’s Ark is aimed at collecting eggs, embryos(胚胎), semen and DNA of endangered animals and storing them in liquid nitrogen(氮). If certain species should become extinct, Dr. Duane Kraemer, a professor in Texas A & M’s College of Veterinary Medicine, says there would be enough of the basic building blocks to reintroduce the species in the future.
It is estimated that as many as 2, 000 species of mammals, birds, reptiles will become extinct in over 100 years. The panda, native only to China, is in danger of becoming extinct in the next 25 years.
This week, Chinese scientists said they grew an embryo by introducing cells from a dead female panda into the egg cells of a Japanese white rabbit. They are now trying to implant the embryo into a host animal.
The entire procedure could take from three to five years to complete.
“The nuclear transfer(核子移植) of one species to another is not easy, and the lack of available(capable of being used) panda eggs could be a major problem,” Kraemer believes. “They will probably have to do several hundred transfers to result in one pregnancy (having a baby). It takes a long time and it’s difficult, but this could be groundbreaking science if it works. They are certainly not putting any live pandas at risk, so it is worth the effort,” adds Kraemer, who is one of the leaders of the Project at Texas A& M, the first-ever attempt at cloning a dog.
“They are trying to do something that’s never been done, and this is very similar to our work in Noah’s Ark. We’re both trying to save animals that face extinction. I certainly appreciate their effort and there’s a lot we can learn from what they are attempting to do. It’s a research that is very much needed.”
60. The aim of “Noah’s Ark” project is to _______.
A. make efforts to clone the endangered pandas 
B. save endangered animals from dying out
C. collect DNA of endangered animals to study
D. transfer the nuclear of one animal to another
61. According to Professor Kraemer, the major problem in cloning pandas would be the lack of _______.
A. available panda eggs                B. host animals
C. qualified researchers                D. enough money
62. The best title for the passage may be _______.
A. China’s Success in Pandas Cloning                       
B. The First Cloned Panda in the World
C. Exploring the Possibility to Clone Pandas  
D. China —the Native Place of Pandas Forever
63. From the passage we know that _______.
A. Kraemer and his team have succeeded in cloning a dog
B. scientists try to implant a panda’s egg into a rabbit
C. Kraemer will work with Chinese scientists in clone researches
D. about two thousand of species will probably die out in a century