氢硒化钠

Broadcast: February 14, 2003 By George Grow This is the VOA Special English Environment Report. President Bush has offered a plan to speed development of technology that uses hydrogen as fuel. His goa

发表于:2018-12-07 / 阅读(74) / 评论(0) 分类 VOA2003(上)-科技导航

I am speaking not as a Briton, not as a European, not as a member of a western democracy, but as a human being, a member of the species Man, whose continued existence is in doubt. The world is full of conflicts: Jews and Arabs; Indians and Pakistanis

发表于:2018-12-12 / 阅读(54) / 评论(0) 分类 英语演讲

Salt is believed to be the single most harmful thing in our food, contributing to high blood pressure For years doctors have been telling patients with high blood pressure to cut down on the amount of salt in their diet. Now a prestigious panel of ex

发表于:2019-01-13 / 阅读(76) / 评论(0) 分类 VOA标准英语2010年(四)月

PREFIX 1.a-:of;on;intensive;negative,not,without;ad-;ab-. 2.ab-:away from,off. 3. ad-:to;at;for. 4. aer(o)- :relating to air . 5.al-:all. 6.ambi-:on both sides,around. 7.amphi-:on both sides,around. 8.an-:negative,not,without. 9.ana-:upon,up,on. 10.a

发表于:2019-02-06 / 阅读(100) / 评论(0) 分类 雅思英语

December 30, 1954 I am speaking not as a Briton, not as a European, not as a member of a western democracy, but as a human being, a member of the species Man, whose continued existence is in doubt. The world is full of conflicts: Jews and Arabs; Indi

发表于:2019-02-09 / 阅读(45) / 评论(0) 分类 英语美文

Oxygen itself is not combustible; it merely facilitates the combus tion of other things. (氧本身是不可燃的,它只是帮助别的东西燃烧。 This is just as well, for if oxygen were corn bustible, each time you lit a match all the air

发表于:2019-02-25 / 阅读(46) / 评论(0) 分类 万物简史