设备在闲置过程中，由于自然力的作用而腐蚀，或由于管理不善和缺乏必要的维护而自然丧失精

下列选项中，属于显示器性能指标的是()。

A.速度

B.可靠性

C.分辨率

D.精度

将等物质的量的Na₂O和Na₂O₂分别投入到足量且等质量的水中，得到溶质质量分数分别为％和％的两种溶液，则和的关系是

A．＝

B．>

C．<

D．无法确定

Object-oriented analysis (OOA) is a semiformal specification technique for the object-oriented paradigm. Object-oriented analysis consists of three steps. The first step is (71) . It determines how the various results are computed by the product and presents this information in the form of a (72) and associated scenarios. The second is (73) , which determines the classes and their attributes, then determines the interrelationships and interaction among the classes. The last step is (74) , which determines the actions performed by or to each class or subclass and presents this information in the form of (75) .

（75）处填（）。

A. state diagram

B. collaboration diagram

C. sequence diagram

D. activity diagram

93#车用乙醇汽油与93#车用汽油相比，93#车用乙醇汽油有（）的特点。

A.吸湿性较强

B.清洁性差

C.抗爆性能差

D.污染大

检测仪表检修或校准时，（）

A.必须做好校准前检查性校验记录和校准后校验记录

B.校验记录应正确、字迹清晰端正、结论明确，具有校验人、校对人的签名和校验日期

C.如对其内部电路、机构或测量量程等作了修改，应在校验记录中说明。常规检修内容校验记录中可不填写

D.校验记录至少应保持1个大修周期