Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in microns. One micron is a thousandth of a millimeter: a pinhead is about a millimeter across. Rod-shaped bacteria are u

发表于:2018-11-28 / 阅读(424) / 评论(0) 分类 新概念优美背诵短文50篇

Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in microns. One micron is a thousandth of a millimeter: a pinhead is abo

发表于:2018-12-01 / 阅读(141) / 评论(0) 分类 新东方背诵文选

HEALTH REPORT -May 29, 2002: Staph Vaccine By Nancy Steinbach This is the VOA Special English Health Report. American researchers say they have developed the first vaccine medicine that can prevent a

发表于:2019-01-02 / 阅读(47) / 评论(0) 分类 健康与环境

By Ruth Reader Washington, DC 13 February 2008 There is growing concern around the world over illnesses caused by new antibiotic-resistant bacteria, or so-called superbugs, and the decreasing effectiveness of antibiotics to treat infections. Earlier

发表于:2019-01-07 / 阅读(67) / 评论(0) 分类 VOA常速英语2008年(二月)

Experts: Let Produce Dry Out to Avoid Bacteria American researchers say farmers should wait one day after a rain storm or watering their fields to harvest fresh fruits and vegetables. They say gathering the crops at least 24 hours after rainfall incr

发表于:2019-01-12 / 阅读(112) / 评论(0) 分类 2015年VOA慢速英语(七)月

Water allows the sand grains to flow to gather and intermingle and form more complex structures. In the same way, water acts like a cocktail mixer, allowing the atoms and molecules to come together, and also may form the building blocks of life. All

发表于:2019-01-22 / 阅读(37) / 评论(0) 分类 自然百科2010年