CR Bible 全面总结！！！！！！！！！！

XYZQUE · 发表于 2014-8-14 10:00:00

加油加油！！！

dddemi · 发表于 2014-8-14 11:20:56

谢谢！！！！！！！！！！！！！！

oooook0 · 发表于 2014-8-14 11:27:08

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lvanlee · 发表于 2014-8-14 16:15:48

Outbreaks of Rift Valley fever occur irregularly in East Africa, several years apart. When outbreaks do occur, they kill thousands of cattle. A livestock vaccine against the disease exists but is rarely used. It is too expensive for farmers to use routinely, and since it is not effective until a month after vaccination, administering it after an outbreak begins helps very little. Nevertheless, experts predict that use of the vaccine will increase significantly within the next few years.