对阵发性室性心动过速伴明显血流动力学障碍者，首选治疗是

A．利多卡因静脉点滴
B．立即进行射频消融术
C．休外直流电同步电复律
D．西地兰静脉注射

Geography is the study of the relationship between people and the land. Geographers compare and contrast various places on the earth. But they also (51) beyond the individual places and consider the earth as a whole. The English word geography means "to describe the earth. " (52) geography books focus on a small area like a town or city. Others deal with a state, a region, a nation, or an (53) continent. Many geography books deal with the whole earth. Another (54) to divide the study of geography is to distinguish between physical geography and cultural geography. The former focuses on the natural world; the (55) starts with human beings and studies how human beings and their environment act (56) each other. But when geography is considered as a single subject, (57) branch can neglect the other. A geographer might be described as one who observes, records, and explains the (58) between places. If all places (59) alike, there would be little need for geographers. We know, however, that no two places are exactly the same. Geography, (60) is a point of view, a special way of looking at place.

58().

A.exceptions 

B.sameness 

C.differences 

D.divisions