light to attract objects. at least at a microscopic level

　　Light control techniques have existed since the l970s. but this is thought to be the first

　　time a beam has been used to draw objects towards a light source

　　Usually when microscopic

　　objects are hit by a line of light. they are forced along the direction of the beam

　　After many

　　years' research. Dr Cizmar's team discovered a technique that allows for the radiant force(辐射力) of light to be changed and to use the negative force to draw out certain particles（小颗粒）

　　Dr Cizmar says that even though it is a few years away from practical use. the technology　 has huge potential for medical research

　　In particular. the tractor beam is highly selective in　 the particles it can attract. so it can pick up particles that have specific characteristics. such as　 size or composition. in a mixture

　　"Eventually, this could be used to separate white blood　cells. for example," Dr Cizmar told BBC News

　　It has been a primary plot design in science fiction TV programs and movies to allow objects like spaceships to be trapped in a line of light But Dr Cizmar said this particular technique would not eventually lead to that A transfer of energy happens in the process

　　On a microscopic level that is OK. but on a large level it would cause huge problems

【2017届湖北省黄冈市高考英语阅读理解二轮精练：31（含解析）】相关文章：

★ 2017届高考英语二轮复习大题冲关秘籍短文改错：解题策略（含解析）

★ 【优化方案】2017届高考英语二轮复习全国卷Ⅱ规范练：7（含解析）

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (17)

★ 2017高考四川省广安市英语阅读理解一轮系列训练：27（含解析）

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (43)

★ 【课堂新坐标】2017届高考英语（通用版）二轮复习书面表达专题训练：训练2 书信、邮件＋写人类记叙文（含解析）

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (45)

★ 2014高考英语（新人教版）一轮基础训练（18）A、B卷（附答案或解析）

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (37)

★ 重庆市2014高考英语阅读理解一轮（精品）训练题（16）附答案