如果一直线电流的方向由北向南，在它的上方放一个可以自由转动的小磁针，则小磁针的N极偏

马克思说：“火药、罗盘针、印刷术——这是预兆资产阶级社会到来的三项伟大发明。”这句话反映出( )。

A．中国古代发明孕育了西方近代文明
B．西方资产阶级将利用这些发明进行侵略扩张
C．在特定条件下科技发明对历史发展产生重大影响
D．三项伟大发明蕴含资本主义因素

患者，20岁。深龋，曾有过夜间疼痛，遇冷热痛。检查：龋未穿髓，电测反应迟钝，叩诊（±）。应诊断为（）

A.可复性牙髓炎

B.慢性闭锁性牙髓炎

C.慢性增生性牙髓炎

D.慢性溃疡性牙髓炎

E.牙髓坏死

新型干法水泥生产方法

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] learn [B] learnt [C] was learning

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