In history.the Romany split into different groups and developed their own language. there are now approximately sixty varieties．( )A．by whichB．of whichC．by whomD．of whom 题目和参考答案——青夏教育精英家教网—

12．President Barack Obama rode a bicycle at the White House Science Fair on April 22．But it wasn't an ordinary bike．As he pedaled，the President stayed in place，while the energy from his pedaling powered a water filtration （过滤） system．He was testing an invention created by a team of 14students from Northeast High School，in Oakland Park，Florida．
Payton Karr，16，and Kiona Elliot，18，attended the fair as representatives of the project．"We were hoping President Obama would ride the bike，but we didn't actually expect him to，"Payton told TFK．"It really meant a lot．"Kiona agreed．"It was pretty awesome to see the invention，which was invented by a group of 14high school students and one teacher，along with the help of community members，got the interest of the leader of our nation，"she said．
The project was an idea that came about after one of the Northeast students，Kalie Hoke，visited Haiti after the terrible 2010earthquake and saw how difficult it was to find clean water．The students invented a portable（便携的），bicycle-powered emergency water filtration system，which can provide 20-30people with drinking water in a 15-hour period．The teens hope their invention will one day be used by relief organizations like the Red Cross．"They can take it to places after natural disasters so that water can be clean for the people there，"said Payton．
Payton and Kiona were among the 100students from more than 40states invited to the third annual White House Science Fair，in Washington，D．C．，which is also attended by leaders in science and education．President Obama started the event in 2010to stimulate students interested in STEM （Science，Technology，Engineering，Maths）．"Well，if you're a young person and you produce the best experiment or design，you ought to be recognized for that achievement，"Obama said when he first announced the fair．
President Obama praised the projects during a speech to attendees after the fair．"The science fair projects of today could become the products and businesses of tomorrow，"he said．"If you're inventing things in the third grade，what are you going to do by the time you get to college？"

36．What is special about the bicycle President Obama rode？C
A．It can move very fast．
B．It is extremely beautiful．
C．It is used to make water clean．
D．It is made of eco-friendly materials．
37．The representatives of the bicycle-powered water filtration systemD．
A．were both community members
B．graduated from a famous university
C．finished the project with the help of their parents
D．were surprised that their invention interested Obama
38．The bicycle-powered water filtration system was designedD．
A．at the request of the Red Cross
B．for city families to get pure water
C．during the terrible 2010earthquake in Haiti
D．to provide people in disaster areas with clean water
39．The underlined word"stimulate"in Paragraph 4can be replaced byB．
A．help B．inspire C．change D．entertain
40．We can know from the last sentence in the passage that President ObamaD．
A．wanted the youth to have big dreams
B．encouraged the youth to go to college
C．worried the young inventors would do nothing in college
D．believed the young inventors would have a promising future．

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