Butterfly numbers drop a mystery, say experts 英国蝴蝶数量下降现象令专家费解
Play audio file 英国的蝴蝶数目大量减少，这让野生动植物专家们感到非常费解。一项由成千上万名志愿者参与的年度“蝶口统计”调查显示，与 2013 年每计数次的 23 只相比，今年的平均值降到了 12.2 。此前，蝴蝶数目曾在 2017 年潮湿的夏天骤然下降，本年度的数量甚至比当时还要少。推行这个计划的蝴蝶保护协会（ Butterfly Conservation ）说，造成该现象的原因至今仍是一个谜。请听报道。
Each year, tens of thousands of people take part in The Big Butterfly Count to help experts chart the fortunes of common species.
Some butterflies recorded their worst numbers since the project began in 2010. Sightings of commas were down 46% compared with last year.
Butterfly Conservation says the weather this summer should have helped the insects. It thinks the mild winter and cold spring could have had an effect along with pesticides. But there were some successes – red admirals were up 70% on last year, and green-veined whites were up 58%.
词汇表 The Big Butterfly Count 由英国蝴蝶保护协会推行的“蝶口统计”项目，号召全国志愿者记录并统计不同种类的蝴蝶数量
chart 标示，详细记录
fortunes 时运
numbers 数目，数量
sightings 目击、看见（罕见或珍贵的事物或现象）
commas 白钩蛱蝶
red admirals 优红蛱蝶
green-veined whites 暗脉菜粉蝶
测验 请听报道并回答下列问题。
1. Why do tens of thousands of people take part in The Big Butterfly Count?
2. In which year did the project start running?
3. True or false? The drop in the number of butterflies was across all species.
4. Which word in the text means ‘chemicals used to kill harmful insects’?
答案 1. Why do tens of thousands of people take part in The Big Butterfly Count?
They take part in The Big Butterfly Count to help experts chart the fortunes of common species.
2. In which year did the project start running?
The project began in 2010.
3. True or false? The drop in the number of butterflies was across all species.
False. Some species, such as red admirals and green-veined whites, were doing well.
4. Which word in the text means ‘chemical products used to kill harmful insects’?
Pesticides.