The passage is mainly about ______.
A. an approach to patents
B. the application for patents
C. the use of patents
D. the access to patents
Georges Valensi's patent lasted until 1971 because ______.
A. nobody would offer any reward for his, patent prior to that time
B. his patent could not be put to use for an unusually long time
C. there were not enough TV stations to provide color programmes
D. The color TV receiver was not available until that time
弥漫性肝实质病变简便实用的影像学检查方法是
A. 磁共振(MRI)
B. 选择性肝动脉造影
C. 超声
D. CT
E. 单光子发射型计算机断层仪(SPECT)
患儿，男，5岁，心脏超声检查示升主动脉与主肺动脉间隔连续性中断约5mm，探及左向右过隔血流信号，频谱为双期连续，考虑为
A. 动脉导管未闭
B. 主肺动脉窗
C. 右室双出口
D. 室间隔缺损
E. 以上都不是
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