Global warming is a big problem that we have to stop． One of the best things we do is to plant more trees． Trees can take in CO2 in the air and stop global warming．（1） 　　

A team of scientists at Boston University has been working with NASA to study Earths green vegetation（植被）． They used a special NASA camera and found that global leaf area had increased by 5 percent since the early 2000s． （2） 　　That's about one﹣quarter of the size of the entire Amazon rainforest．

The growth mainly came from China's forest protection programs， NASA said． For example， since 1962． China has been planting trees in Saihanba． Hebei Province． It was once a desert，（3） 　　

（4） 　　Ant Forest， a feature in Alipay app， gives users points for doing eco﹣friendly things such as walking and going paperless in the office． Users can then use these points to water and grow their own virtual（虚拟的）trees． When the virtual trees are big enough， Ant Forest will plant real trees somewhere in the world．（5） 　　

A． More than 55 million trees have been planted in this way．

B． The Chinese public has also joined in these activities recently．

C． And China was responsible for 25% of that gain． according to the study．

D． However， people there can produce vegetables without any difficulty now．

E． But now， China has turned the area into the country's largest man﹣made forest．

F． According to a news report， China is doing a great job of"greening"the world．