宿主的天然抵抗力A．经遗传而获得 B．感染病原微生物而获得 C_爱下问搜题

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问题单项选择题

宿主的天然抵抗力

A．经遗传而获得

B．感染病原微生物而获得

C．接种菌苗或疫苗而获得

D．母体的抗体(IgG)通过胎盘给婴儿而获得

E．给宿主转输致敏巴细胞而获得

答案

参考答案：A

选择题

The Expo 2010 Shanghai China has been a successful event. If it _____ for one more week, we might have

visited all the pavilions. [ ]

A. continues

B. had continued

C. continued

D. has continued

填空题

紧急阀主要由（）、阀座、弹簧、活塞、活塞杆和电磁阀组成。