A few cups of green tea each day may help prevent heart disease,Greek researchers said
on Wednesday.A study published in the European Journal of Cardiovascular (心血管的)
Prevention showed further evidence of the potential health benefits from tea already linked
to a reduced risk of a range of cancers and other conditions.
The study showed that green tea improves blood flow and the ability of arteries (动脉)
to relax,said Charalambos Vlachopoulos,an expert at the Athens Medical School in Greece
who worked on the study.
Other studies have shown that black tea also has benefits for cardiovascular health.
The Greek team said they believed green tea might be even better because it had higher
quantities of beneficial substances called flavonoids (类黄酮)-some of which are lost 
in the
oxidation (氧化) process that black tea undergoes.
Flavonoids are also found in cocoa,tomatoes and grapes."A couple of cups a day would
probably be good for people," Vlachopoulos said."This is the first study to show these
effects for green tea."
The researchers gave 14 healthy volunteers either green tea,coffee or hot water and then
measured the function of endothelial cells (内皮细胞)．These cells help relax arteries and
ease blood flow."What is important is these effects are evident within 30 minutes,"
Vlachopoulos said.
The measurements taken 30,90 and 120 minutes following consumption showed an
almost immediate benefit among people who had drunk green tea,he said.While the researchers
looked only at a short-term effect,Vlachopoulos said the team's studies suggest the protection
is long-lasting.
"Green tea is consumed less in the Western world than black tea,but it could be more
beneficial,"he said.
1．What would be the best title for the passage?_____
A．B
enefits from black tea
B．Different kinds of tea
C．Green tea protects against heart disease
D．Green tea reduces the risk of cancer
2．According to the study,green tea can do the following EXCEPT________.
A．improve blood flow
B．benefit cardiovascular health
C．help relax arteries
D．increase the oxidation rate of flavonoids
3．Which of the following statements is TRUE?______
A．Green tea is better than black tea because it has been processed.
B．Green tea contains more flavonoids than black tea.
C．Vlachopoulos's study is based on many years' research.
D．Vlachopoulos's study is the first to show green tea's benefits.
4．We can learn from the passage that________.
A．14 volunteers with heart disease joined in the experiment
B．it takes an hour for green tea to take effect
C．green tea has a long－lasting effect according to Vlachopoulos
D．Westerners prefer green tea to black tea
5．Which one of the following factors is NOT related with the research procedure?______
A．The volunteers.
B．The drinks.
C．Blood samples.
D．Objects for time－measuring