A:体液大量流失
B:非特异性免疫能力减弱
C:特异性免疫能力减弱
D:营养物质得不到及时的补充
Have you the people here? It is said that they have a kind of strange illness.
从1,2,3,4这四个数字中依次取(不放回)两个数a,b,使得a2≥4b的概率是( )
下列地区,地处暖温带、半湿润地区、温带季风气候的是( )