For centuries,tea has been used for far more than overcoming thirst.Around the world people drink it to relax and restore energy.
Green,oolong and black tea come from the same plant — Camellia sinensis（茶树）.Green tea,however,is processed in a different way,which results in higher levels of some of the compounds that scientists believe have positive effects on our mental health.
A 2017 review of more than 100 studies found that green tea can impact the brain in three ways：reduce anxiety；focus attention；and improve brain function,especially memory.However,it was cautioned that the effects aren't large,and current evidence is mainly provided by small-scale studies.
There are also suggestions that tea could improve the symptoms of depression,dementia（痴呆）and Down syndrome （唐氏综合征）.
A 2018 study conducted in South Korea found that frequent green tea drinkers were 21% less likely to develop depression than those who were non-drinkers.However,as an observational study,it couldn't establish cause and effect,only association.
Tea also has some benefits for our physical health — it's linked to a longer life,could reduce some risk factors for cardiovascular（心血管的） disease such as heart attack and stroke,and may also have a weight-losing effect.
"We need better data to truly assess the benefits of tea on our mental and physical well-being," said Gunter Kuhnle at the University of Reading,"however,with the exception of green tea pills,which have been linked to liver damage,and burning tea,which has been linked to esophageal（食道的）cancer,there's no real downside to a cup of tea.I think most people enjoy rituals（仪式感）.It's a comforting thing.If there's anything wrong,here it's a cup of tea that's needed."



How is green tea different from oolong and black tea？ ______

A. It cures depression and dementia.
B. It is never part of a complex ritual.
C. It has higher levels of certain compounds.
D. It is taken from Camellia sinensis.

What does Gunter Kuhnle want to express？ ______

A. Green tea rituals give people comfort.
B. Green tea pills may cause esophageal cancer.
C. Green tea brings people more harm than good.
D. Green tea proves beneficial with no exception.

Which can be a suitable title for the text？ ______

A. Which tea prevents cancer
B. Why drinking tea might help
C. When tea causes liver damage
D. How teas are processed