将样品水垢研磨成粉末，用磁铁检查水垢样品的磁性，若磁性（）说明含有大量氧化铁。 A.

下列何种显像剂是脑受体显像剂（）

A.^99mTc-HMPAO

B.¹²³I-IMP

C.^99mTc-ECD

D.¹²³Xe

E.¹²³I-IBZP

给下面的新闻拟一个合适的标题。

　　共青团中央、教育部、人力资源和社会保障部联合举办的“我的青春故事”全国优秀中职毕业生报告会今天在北京举行。中 * * 政治局委员、全国人大常委会副委员长王兆国会见报告团全体成员，要求广大中职学生坚定理想信念，勤奋刻苦学习，钻研专业技能，为加快经济发展方式转变、保持经济平稳较快发展做出更大的贡献。

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A major new development in system of work in Britain is taking place. Flexible working hours, or “Flextime”, are catching on fast, and trend is continuing. In 1973, over 500 organizations had adopted the idea, and by 1974, this number had risen to over 200,000.

Flexible working hours were invented in Germany in the late 1960’s, but reached Britain only in 1972. The system allows workers to start and finish work whenever they want, with only two requirements. These are, firstly, that all workers must present for certain “key” times in the day, and secondly, that all workers must work an agreed total number of hours per week.

The system had proved a total success wherever it has been tried. A survey of 700 workers on flexible hours showed three main advantages: a better balance between working and private life, avoidance of the need to travel during rush hours and the ability to finish a certain task before leaving.

From the employer’s point of view, the system tends to increase productivity, reduce labour turnover and give workers a greater sense of duty. At first, “Flexible” was mainly confined to white-collar workers, but it is now being applied to manual workers too.

小题1:According to “Flextime” system, workers need not _________.

A．work at the same time

B．work all the weekdays

C．work hard

D．ask for leave when being absent小题2:“Key” time is a period when _________.

A．visitors come to the plants

B．all workers must be at work

C．employers go round in the workshop

D．rush hours are over小题3:No matter where it is used, this system has proved _________.

A．entirely effective

B．totally correct

C．a complete failure

D．quite difficult小题4:One of the great advantages of “Flextime” for workers is that they _________.

A．have a great sense of duty

B．can avoid busy traffic

C．can get higher pay

D．can avoid working hard

当1号机或2号机其中一台机组的厂用电由工作电源带，另一台机组的厂用电由备用电源带时，此方式下哪些开关严禁合环？

海拔1000m以下地区，在500kV交流输电线路上进行带电作业时，绝缘绳索最小有效绝缘长度为（）。

A.0.7m

B.1.8m

C.2.8m

D.3.7m