团注静脉肾盂造影术步骤。错误的是

A．注射对比剂前摄腹部平片

B．注射对比剂后1分钟和5分钟行双肾摄片

C．注射对比剂后20分钟摄腹部平片和双侧斜位片

D．解除压迫后行膀胱摄片

E．排空后再摄腹部平片

Many students do not like tostudy history(历史)．They say that there are (41) many names and dates to (42) ．But if we do not know about the (43) ，we can not understand the present well．For example，if we wish to know how men (44) to use fire，we have to know what men did (45) the past to travel at night or to keep themselves (46) in cold nights．Only a study of history will make US realize(意识到) (47) everything we do today is the result of what (48) people did in the past．

[A] too [B] enough [C] nearly

As we (49) history，we learn many interesting (50) ．History helps US understand our present life better．