There is good news and bad news regarding the number of trees on our planet. The good news is that there are seven times more trees on Earth than we thought. Until a few years ago, scientists estimated that the world had around 400 billion trees. However, a new study from Yale University estimates that there are around three trillion trees. That's a three followed by 12 zeroes. That means there are more than 420 trees for every person alive today. Lead researcher Dr Thomas Crowther told the BBC that the new estimate will not change anything. He said: "It's not like we've discovered a load of new trees. It's not good news for the world or bad news that we've produced this new number."
The bad news is that thousands of years ago, the earth had around six trillion trees. Human activity has cut in half the number of trees on the planet. A good example of this is the fact that Europe used to be one giant forest. Now much of it is farmland, fields, cities and towns. Dr Crowther said people are responsible for the loss of three trillion trees over the past several thousand years. Humans are destroying around 15 billion more trees every year because of deforestation and the demand for farmland. The scientists said this figure is "considerably higher" than just a century ago. Dr Crowther warned that: "This study highlights how much more effort is needed if we are to restore healthy forests worldwide."
1.a load of 许多
例句：I have a baby and with our family of four, I do a load of laundry almost every week day.
我家一共有四个人，包括一个婴孩。 我几乎每个工作日都要做大量的洗衣工作 。
2.used to be 过去曾经是
例句：I am not who I used to be. How can I go back?
3.because of 因为
例句：It is mainly because of my fault.
4.responsible for 为…负责
例句：He should be responsible for that.
1.How many times more trees are there than we thought?
2.How many trees did scientists originally think we had?
a) 200 billion
b) 300 billion
c) 400 billion
d) 500 billion
3.How many trees do scientists now think we have?
a) 6 trillion
b) 5 trillion
c) 4 trillion
d) 3 trillion
4.How many trees are there for each person in the world today?
5.What did a scientist say the new number of trees would change?
6.How many trees were there on Earth thousands of years ago?
a) 3 trillion
b) 4 trillion
c) 5 trillion
d) 6 trillion
7.What does the article say Europe use to be?
a) a desert
c) a giant forest
8.How many trees are humans destroying each year?
a) 14 billion
b) 15 billion
c) 16 billion
d) 17 billion
9.What period of time did scientists compare the annual loss of trees to?
a) a thousand years ago
b) 500 years ago
c) 100 years ago
d) 10 years ago
10.What is needed to restore healthy forests worldwide?