计算机病毒通常是________。

A、一段程序代码
B、一个文件
C、一个标记
D、一条命令
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正确答案:

A

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Thetroublewiththechemicalindustryisthatwhenthingsgowrongtheyoftencausedeathtothoselivingnearby.Itisthiswhichmakeschemicalaccidentssonewsworthy.Fortunately,theyareextremelyrare.ThemostfamousoneshappenedatTexasCity(1947),Flixborough(1974),Seveso(1976),Pemex(1984)andBhopal(1984)。

Someofthesearealwaysinthemindsofthepeopleeventhoughthelossoflifewassmall.NoonediedatSeveso,andonly28workersatFlixborough.TheworstaccidentofallwasBhopal,whereupto3,000werekilled.TheTexasCityexplosionoffertilizerkilled552.ThePemexfireatastorageplantfornaturalgasinthesuburbsofMexicoCitytook542lives,justamonthbeforetheunfortunateeventatBhopal.

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