数据安全是指对信息系统中业务数据的哪几方面进行安全保护。（）A、传输 B、存储 C、

关于幽门螺杆菌感染的诊断正确的是（）。

A.¹³C或¹⁴C呼气试验是根除治疗后复查的首选方法

B.近期使用PPI或抗生素可导致血清幽门螺杆菌抗体检测呈阴性

C.使用抑酸药者应在停药至少2周后进行幽门螺杆菌感染相关检查

D.快速尿素酶试验阳性就可以进行幽门螺杆菌根除治疗

E.萎缩性胃炎可能使除血清抗体检测外的幽门螺杆菌检测方法呈现假阴性

The students were participating             an international energy saving competition between

towns in New England and Canada.    [ ]

A．for    

B．in    

C．to    

D．at

水下（）焊接，是将焊接区周围的水排开，焊工在水中施焊的水下焊接方法。

A.干法

B.局部干法

C.湿法

Insurance is the sharing of (1) . Nearly everyone is exposed (2) risk of some sort. The house owner, for example, knows that his (3) can be damaged by fire; the ship owner knows that his vessel may be lost at sea; the breadwinner knows that he may die by (4) and (5) his family in poverty. On the other hand, not every house is damaged by fire or every vessel lost at sea. If these persons each put a (6) stun of money into a pool, there will be enough to (7) the needs of the few who do suffer (8) . In other words the losses of the few are met from the contributions of the (9) . This is the basis of (10) . Those who pay the contributions are known as (11) and those who administer the pool of the contributions as insurer.
The (12) for an insurance naturally depends on how the risk is to happen as suggested (13) past experience. If the companies fix their premiums too (14) , there will be more competition in their branch of insurance and they may lose (15) . On the other hand, if they make the premiums too low, they will not have (16) and may even have to drop out (17) business. So the ordinary forces of supply and (18) keep premiums at a proper (19) to both insurers and those who (20) insurance.

户内树脂浇注互感器外绝缘应有满足使用环境条件的爬电距离并通过凝露试验。