关于叶酸的描述，下列哪项是正确的（）. A.不耐热 B.在酸性环境中不稳定 C.存在

计算机病毒是一种侵入计算机系统并具有潜伏性、寄生性、传染性和破坏性的( )。

A．生物

B．细菌

C．程序

D．指令

工程管理信息化属于( )的范畴。

A．领域信息化

B．区域信息化

C．结构信息化

D．技术信息化

患者大便时溏时泻，水谷不化，稍进油腻之物，则大便次数增多，食少，脘腹胀闷，面黄，肢倦乏力，舌淡苔白，脉细弱。治疗应首选

A．四君子汤
B．大建中汤
C．参苓白术散
D．小建中汤
E．补气运脾汤

容器的封头主要分哪几种？

Do mobile phones cause explosions at petrol stations That question has just been exhaustively answered by Adam Burgess, a researcher at the University of Kent, in England. Oddly, however, Dr Burgess is not a physicist, but a sociologist. For the concern rests not on scientific evidence of any danger, but is instead the result of sociological factors: it is an urban myth, supported and propagated by official sources, but no less a myth for that. Dr Burgess presented his findings this week at the annual conference of the British Sociological Association.

Mobile phones started to become widespread in the late 1980s, when the oil industry was in the middle of a concerted safety drive, Dr Burgess notes. This was, in large part. a response to the Piper Alpha disaster in 1988, when 167 people died in an explosion on an oil platform off the Scottish coast. (41)__________So nobody questioned the precautionary ban on the use of mobile phones at petrol stations. The worry was that an electrical spark might ignite explosive fumes.

(42)__________But it was too late. The myth had taken hold.

One problem, says Dr Burgess, is that the number of petrol-station fires increased in the late 1990s, just as mobile phones were proliferating. Richard Coates, BP’s fire-safety adviser, investigated many of the 243 such fires that occurred around the world between 1993 and 2004. He concluded that most were indeed caused by sparks igniting petrol vapour, but the sparks themselves were the result of static electricity, not electrical equipment. Most drivers will have experienced a mild electric shock when climbing out of their vehicles. It is caused by friction between driver and seat, with the result that both end up electrically charged. When the driver touches the metal frame of the vehicle, the result is sometimes a spark. ( 43 )__________

(44)__________One e-mail contained fictitious examples of such explosions said to have happened in Indonesia and Australia. Another, supposedly sent out by Shell, found its way on to an internal website at Exxon, says Dr Burgess, where it was treated as authoritative by employees. Such memos generally explain static fires quite accurately, but mistakenly attribute them to mobile phones. Official denials, says Dr Burgess, simply inflame the suspicions of conspiracy theorists.

(45)__________Warning signs abound in Britain, America, Canada and Australia. The city of Sao Paulo, in Brazil, introduced a ban last year. And, earlier this month, a member of Connecticut’s senate proposed making the use of mobile phones in petrol stations in that state punishable by a $ 250 fine.

[A] The safety drive did not apply merely to offshore operations: employees at some British oil-company offices are now required to use handrails while walking up and down stairs, for example.

[B] As a result, the company had to pay a huge amount of compensation to the families of the victims and law suits concerning those fires seemed to be endless.

[C] A further complication was the rise of the internet, where hoax memos, many claiming to originate from oil companies, warned of the danger of using mobile phones in petrol stations.

[D] This is particularly noticeable in Britain. The country that led the way in banning mobile phones at petrol stations is also the country that has taken the pest line on the safety of mobile-phone use by children.

[E] Despite the lack of evidence that mobile phones can cause explosions, bans remain in place around the world, though the rules vary widely.

[F] By tile late 1990s, however, phone makers—having conducted their own research— realized that there was no danger of phones causing explosions since they could not generate the required sparks.

[G] This seems to have become more common as plastic car interiors, synthetic garments and rubber-soled shoes have proliferated.

41（）