问题 单项选择题

梯度磁场工作状态错误的内容是()

A.呈开关状态工作

B.在脉冲序列中可有不同幅度

C.梯度改变的幅度与速率必须精确

D.在心脏MRI时由门控确定其速率

E.在计算机控制下供应电流

答案

参考答案:D

解析:梯度磁场仅在扫描时产生,即处在开关状态或脉冲状态。梯度磁场切换时会产生感应电流,感应电流的大小与磁场梯度的变化率有关。在心脏MRI检查时,常应用回顾性心电门控技术。对于电流控制都是由电脑自动控制,由专门机柜来处理。

阅读理解

As the first woman Chancellor( * * ) in German’s history, Angela Merkel topped Forbes magazine’s list of “The World’s 100 Most Powerful Women” in 2006, 2007, 2008, and 2009.She has even been compared to Margaret Thatcher and many people called her  “Iron Lady”.

Merkel was born in Hamburg, West Germany, on July 17, 1954.Six weeks after she was born, her family moved to Templin. As a small child, Merkel quickly learned to speak but took longer to walk. “I was a stupid person when it came to moving?” Merkel said. “A normal person could do something naturally, but I had to think about it in my mind and practice.” As a teenager, she was the top student and graduated from high school with perfect marks. In 1973, Merkel went to the University of Leipzig, where she studied physics. At 32, she got her doctor’s degree in physics.

She stepped_into_politics in 1989.In her first big political job as Minister for the Environment in 1994, her scientific background and strong will proved very useful. In 2005 she became Germany’s Chancellor. She has been reelected to a second term as German Chancellor on September 27, 2009.

Through her political career, Merkel’s persistence (坚持) and patience helped her a lot. “She’s bright and open­minded,” said Hubert Markl. “She is the person who wants to know exactly what is going on, and how never giving up will influence our society and future.”

小题1:As a small child, Merkel was slow in ________.

A.speaking

B.walking

C.learning

D.thinking小题2:The underlined phrase in Paragraph 3 most probably means “________”.

A.fought the government

B.began her scientific career

C.offered political guidance

D.became a government official小题3:We can infer from the passage that Angela Merkel ________.

A.is a powerful woman with a strong will and determination

B.got her doctor’s degree in politics in University of Leipzig

C.has worked as German Chancellor since Sep.27, 2009

D.showed her best talent as Minister for the Environment小题4:In the last paragraph the author mainly wants to express ________.

A.one must be brave in the political career

B.one should be patient when making decisions

C.persistence can help one’s dream come true

D.one can have a strong will when others haven’t小题5:What’s the author’s attitude toward Angela Merkel?

A.Admiring.

B.Thankful.

C.Pitiful .

D.Dull.

单项选择题