题目内容：

    Gold is one of the rarest materials on Earth and has always been considered a valuable and precious resource. It's very likely that someone in your family owns something made of gold, especially since China is one of the world's biggest buyers of gold jewellery. It's even in our smartphones - they contain parts made from this expensive material.

But where does this beautiful metal actually come from? The answer: outer space.

This August, Chinese scientists became the first in the world to witness gravitational waves（引力波）caused by the collision of neutron (中子）stars, reported Xinhua News Agency.

The sight was witnessed at China's Kunlun Antarctic Station at the South Pole, and Insight, China’s first X-ray astronomical satellite, also contributed to the discovery.

Although collisions of black holes have been recorded before, this was the first time that two neutron stars were known to have collided. It's believed that such collisions lead to huge explosions of energy, and even to the creation of precious metals such as gold and silver.

“The collision of neutron stars is like a very large gold factory in the universe,” Jin Zhiping，a researcher at the Purple Mountain Observatory of the Chinese Academy of Sciences, told Xinhua.

According to an article published by space.com, scientists have long believed gold and other materials are created in this way, but it wasn't until the recent collision that their theory was confirmed.

“The origin of the really heaviest chemical elements in the universe had confused the scientific community for quite a long time,” Hans-Thomas Janka, a senior scientist at the Max Planck Institute for Astrophysics in Germany, said in a news release. “Now, we have the first observational proof for neutron star mergers(合并) as sources.”

Indeed, the recently observed collision is thought to have produced an amount of gold that would weigh 10 times more than Earth, according to New Scientist

Don’t expect to be showered in gold any time soon, however. The collision actually took place 130 million years ago, taking all that time for the event's light to reach Earth.

But at least if you want to see a piece of space up close, all you have to do is to look at the ring on your mom's finger - or the smartphone in your pocket.

1.What's the author's purpose of writing the first two paragraphs?

A. To emphasize the rareness of gold.

B. To list some uses of gold in daily life.

C. To explain the reasons for the popularity of gold.

D. To interest readers about the source of gold.

2.What would the collision of neutron stars lead to according to Xinhua?

A. The creation of black holes.

B. The death of the stars.

C. The disappearance of gravitational waves.

D. The creation of gold.

3.What’s the text mainly about?

A. China’s Kunlun Antarctic Station does research into gold.

B. Collisions between two neutron stars result in gold

C. Collisions contribute to the discovery.

D. Gold is considered a valuable and precious rescource.

4.What can we learn from the article?

A. The amount of gold produced by the collision was very small.

B. The collision was the largest reported in history.

C. China played a big role in the new discovery.

D. The collision took place 130 years ago.