请把下面的汉语翻译成一句英文：
这些人的故事颠覆了中国在非洲给人们留下的两大虚幻印象：一，中国在非洲完全是为了大宗商品；二，中国人在非洲是步调一致的。
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昨天《每日一句汉译英》参考答案：
请把下面的汉语翻译成一句英文：
为美国卫生机构官员提供咨询的预防疾病服务工作组(The Preventative Services Task Force)说，对身体健康的男子而言，一种叫做PSA的简单验血可能弊大于利。
参考答案：
The Preventative Services Task Force, which advises U.S. health officials, says the simple blood test called a PSA may do more harm than good in healthy men.
原文：
一些专家不主张定期做前列腺癌检查(US Panel Recommends Ending Routine Blood Test for Prostate Cancer )
美国政府的一个专家组星期一建议身体健康的男子不要定期做前列腺癌检查。目前，数百万美国男子每年定期做这项检查。
为美国卫生机构官员提供咨询的预防疾病服务工作组说，对身体健康的男子而言，一种叫做PSA的简单验血可能弊大于利。
这个工作组的专家说，PSA检查不能区分非致命与快速发展为致命癌症的前列腺小肿瘤，因此很多男子接受不必要的癌治疗，从而导致性功能障碍或是尿失禁的毛病。
然而，一些美国泌尿学专家对这个工作组的建议提出强烈质疑，认为很多男子可能由于不做PSA检查而死于疼痛的前列腺癌。
在美国，每年有大约三万男子死于前列腺癌。
许多50岁和年过50的男子患前列腺癌。但前列腺癌通常发展缓慢，很多人都不知道知自己患前列腺癌，而且通常是死于其他病症。
A U.S. government panel Monday recommended against healthy men getting a routine test for prostate cancer -- an annual ritual for millions of men.
The Preventative Services Task Force, which advises U.S. health officials, says the simple blood test called a PSA may do more harm than good in healthy men.
The advisors say the test cannot distinguish tiny tumors that are not fatal from fast-growing ones that develop into cancer. They say this results in many men getting unneeded treatment for cancer, leaving them impotent or incontinent.
Some U.S. urologists strongly dispute the panel's recommendation, saying many men could suffer and die a painful death without the tests.
Prostate cancer kills about 30,000 American men a year.
Many men 50 years and older come down with prostate cancer. But the disease often develops so slowly that many victims never know they have it and often die from causes other than prostate cancer.
资料：
Prostate-specific antigen
From Wikipedia, the free encyclopedia
Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), is a glycoprotein encoded in humans by the KLK3 gene. PSA is a member of the kallikrein-related peptidase family and is secreted by the epithelial cells of the prostate gland. PSA is produced for the ejaculate, where it liquefies semen in the seminal coagulum and allows sperm to swim freely.[2] It is also believed to be instrumental in dissolving cervical mucus, allowing the entry of sperm into the uterus.[3]
PSA is present in small quantities in the serum of men with healthy prostates, but is often elevated in the presence of prostate cancer or other prostate disorders.[citation needed] While serum PSA measurement is frequently used in prostate cancer screening, its value is controversial, and the United States Preventive Services Task Force (USPSTF) does not recommend its routine use in healthy men.[4] The USPSTF found that PSA-based prostate cancer screening conveys small or non-existent reductions in prostate-cancer–specific mortality, and is associated with overdiagnosis and over-treatment.[5]
前列腺特异抗原
维基百科，自由的百科全书
前列腺特异抗原（Prostate Specific Antigen ，PSA）血浆前列腺特异抗原浓度升高是提示前列腺癌的敏感监测指标；但不能作为确诊指标。
由于前列腺癌不是造成血浆前列腺特异抗原浓度升高的唯一原因；良性前列腺增生以及感染或人为因素也会引起血浆前列腺特异抗原浓度升高。在前列腺特异抗原测定的基础上，进一步细化；以提高前列腺特异抗原对前列腺癌诊断精确度引入以下概念，为临床工作提供数据鉴别：
f PSA /t PSA：前列腺特异抗原（PSA）有总前列腺特异抗原（tPSA）、结合前列腺特异抗原（cPSA）、游离前列腺特异抗原（fPSA）之分，tPSA= cPSA+ fPSA ；f PSA /t PSA比值对于鉴别前列腺癌与良性前列腺增生比tPSA精确。
前列腺特异抗原密度（PSAD）：即，血浆前列腺特异抗原浓度除以前列腺体积。由于良性前列腺增生是前列腺实质细胞数量增多而造成前列腺体积的增大,常会引起不同程度的血前列腺特异抗原（PSA）浓度升高。有助前列腺癌相与良性前列腺增生症鉴别。
由于前列腺特异抗原（PSA）测试药盒产自多家；t PSA，尤其是 f PSA /t PSA 、PSAD的正常值以测试实验室提供数据为准。
