Dogs have been domesticated for most of human history and have thus endeared themselves to many over the Stories have been told about brave dogs that served admirably in war or that risked their lives to save persons in When Pompeii--the Roman community destroyed by Mount Vesuvius in AD 79--was finally excavated， searchers found evidence of a dog lying across a child， apparently trying to protect the Perhaps few of the millions of dogs in the world may be so heroic， but they are still a source of genuine delight to their
Genetically modified foods have more advantages: increase the crop yield per unit area; can reduce production costs; through transgenic technology can enhance crop resistance to pests， a
; Can make the crop development time is much shorter， Can cast off season， the influence of climate， the four seasons low-cost supply; Breaking boundaries， Living level rising demand;， ;
