阿富汗空军正用直升机向被围城镇提供补给。The Afghan air force was using helicopters to supply the besieged town.这些补给要卸下来装上直升机。The supplies need to be offloaded and put on helicopters.各种补给都不稳定，食品也短缺。Supplies of everything are unreliable, food...
Infectious bursal disease virus ( IBDV ) is an important pathogenic agent of chicken.传染性法氏囊 病毒是鸡的一种重要的病原.The distribution and histology of lymphoid tissue in the Fabricius'bursal stalk were studied.研究了番鸭法氏囊柄部淋巴组织的分布...