[单项选择] New Technique Promises Earlier Cancer Detection A new technique could revolutionize the early detection of cancer, giving sufferers a greater chance of beating the disease, American scientists said. Researchers at the Massachusetts Institute of Technology have devised a novel method of 【51】 changes in the nucleus of cells in the earliest stages of the disease." More than 85 percent of all cancers originate in the epithelium (上皮) that lines the internal surfaces of organs 【52】 the body. Although these are treatable 【53】 they are diagnosed in one of the preventable stages, early body damages are almost 【54】 to detect," said scientist Feld. " We present a new optical-probe (光学探子) technique based on light-scattering spectroscopy (分光镜检查) that is able 【55】 detect precancerous and early cancerous cells in cell-rich epithelia," he added in a statement. The new technique relies on the fact 【56】 cell nuclei change in the early stages of cancer and the differences scatte
A. significantly
B. doubtfully
C. hardly
D. severely

Although the United States has been shaped by continual waves of immigrants, Americans have often viewed immigration as a problem. Established Americans often look down on new immigrants. Despite such tensions, economic needs have always forced Americans to seek immigrants as laborers and settlers, and economic opportunities have appealed to foreigners. The vast majority of immigrants to the United States have come in search of jobs and the chance to create a better life for themselves and their families.
In all of American history, less than 10 percent of immigrants have come for political or religious reasons.
Economic immigrants from Europe, Asia, and Latin America have come to the United States voluntarily. Others, most African Americans, were involuntarily transported to North America to do forced labor or to be sold as slaves. Regardless of the reasons they come to the United States, new immigrants typically work in labor-intensive, low-paying, and d
A. the United States is a nation who hates immigrants
B. the United States is a nation who needs immigrants
C. the United States is a nation of immigrants
D. the United States is a nation who is a melting pot