要知道树龄就得把树砍掉数年轮？不，还有其他办法。

         

                                                                 

   

         What is the oldest living organism on the planet? For scientists, accurately proving the age of any long-lived species is a hard task.
         Under a 300-year-old sweet chestnut tree in the Royal Botanic Gardens in Kew, Tony Kirkham confirms that trees live a long time. Proving this can involve some traditional detective work, as he explains，"First of all, we can look at previous records, to find out if a tree was growing there at a set date. Then we look at paintings and artwork, to look to see if that tree was present. And old survey maps quite clearly show ancient trees, especially important ones."
        A well-known way of measuring the age of a tree is by counting the rings in its trunk: one ring per year of growth. It only works for certain types of trees that have an annual growth spurt. The obvious problem is that counting rings normally involves cutting down the tree. 
        Scientists get around this by using a drill that allows them to take out a core, and count the rings without fatally damaging the tree. It's a delicate art, and, Tony says, back in the 1960s, one scientist's drill broke off inside the pine tree he was sampling. The kit is expensive, and to help him recover the lost instrument, people helpfully cut down the tree. Once fell, the tree could be easily aged, and was found to be 5,000 years old.
        A team of researchers in Britain keep a list, called the Old List, of officially dated ancient trees. They've found a fig tree in Sri Lanka that is at least 2,222 years old. There's a Patagonian cypress tree in Chile which, at 3,627 years old, is as old as Stonehenge. A Great Basin pine in California's White Mountains comes in at 4,850 years old. But the oldest tree on the list, an unnamed pine from the same location, has a core suggesting it is 5,067 years old.

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1.How would the scientists know if the tree lives long?

A They would find a good detective.

B They would paint an old picture.

C They would turn to survey maps.

D They would set down the records.

解析：选C。细节理解题。根据第二段最后一句的And old survey maps quite clearly show ancient trees, especially important ones.可以得知科学家们可以通过看原来的古树木调查地图来知道树的年轮。故选C。

2.What is the disadvantage of measuring the age of a tree by counting rings?

A People would forget the right number easily.

B All of the trees have the annual growth spurt.

C Some have two more rings per year of growth.

D They can’t count the rings without cutting trees.

解析：选D。细节理解题。根据第三段最后一句的The obvious problem is that counting rings normally involves cutting down the tree可以得知，开始的时候如果不砍掉树木就没法数它们的年轮。故选D。

3.Why did people cut down the old tree in the 1960s?

A Because they wanted to finish the delicate art.

B Because they tried their best to take out a core.

C Because they had no way of getting the sampling.

D Because they knew the drill was very expensive.

解析：选D。推理判断题。根据第四段第三句的The kit is expensive, and to help him recover the lost instrument, people helpfully cut down the tree可以得知是因为在当时那个钻头很昂贵，所以他们才把树砍掉。故选D。

4.Which country has the oldest tree in the Old List?

A The USA.

B Chile.

C Sri Lanka.

D Great Britain.

解析：选A。细节理解题。根据第五段最后两句的A Great Basin pine in California's White Mountains comes in at 4,850 years old. But the oldest tree on the list, an unnamed pine from the same location, has a core suggesting it is 5,067 years old中的 California's White Mountains可以得知在美国的那棵树5067岁，是那份清单上最古老的树。故选A。