A、$50.5 million. B、$ 15. 5 million. C、$50.5 billion. D、$ 15.5 billion. B选项都与数字有关。题目问的是美国国立卫生研究院为这个研究小组提供多少资金。文中提到为了建造这个扫描仪，美国国立卫

Scientists are developing a medical device named Explorer that could tell them more about the human body, and help them develop more-effective treatments for cancer, heart disease and brain disorders. It will give medical workers images of what is happening in the entire human body that have never been seen before. It would be the world’s first full-body PET scanner. PET stands for Positron Emission Tomography. PET scanners create 3-D images of what is happening in the body. PET scanners now give doctors images of only parts of the body.
    The U. S. National Institutes of Health gave a research team at the University of California at Davis $ 15. 5 million to build the scanner. Ramsey Badawi is a professor of radiology at UC Davis. He says the scanner will give researchers new information about how human organs work together. ’’We’re a system of organs and all the organs interact with each other. And we’ve never really been able to interrogate that with imaging before, and now we’re going to be able to look at that. ’’
    X-rays and MRIs give images of bones and organs. PET scans show doctors how organs and tissues are working on a molecular level. These images help them identify and follow diseases. The new scanner will help them do that even better. Simon Cherry is a professor of biomedical engineering at UC Davis. He says the PET scans can show the progress of both disease and medical treatments. ’’With PET scans we’re looking at function. We’re actually able to say something about what the cells in the body are doing—how actively they’re metabolizing, for example, or how quickly they’re dividing. Taking a cancer example, that could be tremendously powerful to see if, when you give a drug, whether that shuts down the metabolism of the tumor. ’’
    PET scans use a radioactive substance to find tumors. Professor Cherry says the Explorer uses a much lower amount of radiation than current PET tests, and creates images more quickly. ’’So we can do scans in maybe 30 seconds that currently take 20 minutes. Or we can drop the radiation dose significantly, and do scans at a fraction of the radiation dose that we currently do them at. ’’
    A complete view could help researchers develop new medicines that target diseases and parts of the body. It could help doctors reduce harmful side effects by following the movement of medicines through the body. The researchers hope to test the Explorer with humans in three years.
20. What does the speaker say about Explorer?
21. How much money does the U. S. National Institutes of Health provide to the research team?
22. What will the researchers do in three years?