VOA标准英语2012.12.27
[i=s] 本帖最后由 Rebecca949 于 2012-12-28 10:32 编辑 [/i][audio]http://sound.yywz123.com/tingbbs/voab/voab20121227.mp3[/audio]
Asexual reproduction can be a big advantage, since one bacterium doesn't need another one around to reproduce.无性繁殖是一种很大的优势,因为一个细菌体无需另一个细菌便可繁殖.____________________. In order to add some variety to their genetic makeup, bacteria swap genes with other bacteria. They trade tiny loops of DNA called plasmids. A bacterium makes a plasmid by copying part of its DNA.为丰富它们的基因库,细菌与细菌之间会交易基因.它们所交换的微小的DNA链被称为质粒.一个细菌体通过复制自己的部分DNA生成一个质粒.
**** Hidden Message ***** On the other hand,the bacterium doesn't get genetic diversity.
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