The post office is across ____ the police office. [ ]
A. from
B. of
C. for
D. by
答案:A
GIS内的()会剧烈降低SF6的击穿电压。
A.绝缘微粒;
B.金属微粒;
C.气体杂质;
D.灰尘。
上消化道大出血成人患者1次出血量在多少毫升以上,即可出现休克体征()
A.2000ml
B.1500ml
C.1000ml
D.500ml
E.800ml