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问题 计算题

若我们家里同时使用电饭锅和一盏日光灯，则流经自家电度表的电流有多大？（电饭锅的发热丝电阻约为40Ω，日光灯约1000Ω．）

答案

通过电饭锅的电流为I1===5.5A，

通过日光灯的电流为I2===0.22A，

所以流经自家电度表的电流为I=I1+I2=5.5A+0.22A=5.72A．

单项选择题

Melissa and LoveLetter made use of the trust that exists between friends or colleagues. Imagine receiving an (6) from a friend who asks you to open it. This is what happens with Melissa and several other similar email (7) . Upon running, such worms usually proceed to send themselves out to email addresses from the victim’s address book, previous emails, web pages (8) .
As administrators seek to block dangerous email attachments through the recognition of well-known (9) , virus writers use other extensions to circumvent such protection. Executable (.exe) files are renamed to .bat and .cmd plus a whole list of other extensions and will still run and successfully infect target users.
Frequently, hackers try to penetrate networks by sending an attachment that looks like a flash movie, which, while displaying some cute animation, simultaneously runs commands in the background to steal your passwords and give the (10) access to your network.

A．virtual

B．virus

C．worms

D．bacteria
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选择题

化学与生活密切相关，下列做法合理的是（　　）

A．油着火，用水浇灭

B．电器着火，用泡沫灭火器浇灭

C．用明火检查液化气罐是否漏气

D．在火场的浓烟中逃生，可用湿毛巾捂住口鼻，低姿势前行
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