[单项选择]下列关于MRI检查循环系统的描述错误的是（）
A. MRI仅可从冠状面、矢状面与横断面来显示心脏大血管的解剖结构
B. MRI在循环系统的临床应用广泛
C. MRI可用于检查心脏瓣膜疾病
D. 屏气法MRI电影可观察左室收缩率的变化
E. 心肌标记技术可以鉴别慢速血流和血栓

As the population of the world keeps on growing, it gets more and more difficult to feed everyone. The United States is one of the lucky countries because it grows enough food for itself and still has enough to export to other parts of the world. One reason for this is that the United States is a large country with a variety of climates. Most of the central part of the country is especially suitable for raising grain. Wheat and corn are the most important crops in the region. The United States exports millions of tons of grain every year. Wheat is used to make bread, a basic food throughout the world. Most of the corn is used to feed animals, which in turn become food themselves.
The southeastern part of the United States has a warm, damp climate. It grows cotton, rice and sugar. Florida specializes in fruits and vegetables. It is famous for its orange, lemons and grape. Florida has warm weather all year round, so it can provide vegetables for t