A、B、C、D、E五种元素的原子序数逐渐增大,且均不超过18.其中A与C、B与E

题型:选择题

问题:

A、B、C、D、E五种元素的原子序数逐渐增大,且均不超过18.其中A与C、B与E分别为同族元素.原子半径A<B<E<D<C,B原子最外层电子数是次外层的3倍,C、D的核外电子数之和与B、E核外电子数之和相等.下列说法正确的是(  )

A.原子电子层数:A<B

B.气态氢化物的稳定性:B<E

C.简单离子半径:E<D

D.最高价氧化物对应的水化物碱性:C<D

考点:物质性质的研究
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审贷分离制下,贷款发放人员不负责贷款的清收。( )

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已知|x+y+1|+(x-y+3)2=0,则(x+y)2004等于(  )

A.22004

B.-1

C.1

D.-22004

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计划免疫从预防传染病的角度看属于保护易感人群。[ ]

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Melissa and Love Letter made use of the trust that exists between friends or colleagues. Imagine receiving an (66) from a friend who asks you to open it. This is what happens with Melissa and several other similar email (67) . Upon running, such worms usually proceed to send themselves out to email addresses from the victim’ s address book ,previous emails, web pages (68) .
As administrators seek to block dangerous email attachments through the recognition of well- known (69) , virus writers use other extensions to circumvent such protection. Executable (.exe) files are renamed to . bat and . cnd 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 (70) access to your network.

A.memory

B.caehes

C.ports

D.registers

题型:选择题

家长配合学校教育可以从哪几个方面入手?()

A.主动到学校去拜访老师

B.帮助老师解决其家庭中的问题以解决老师的后顾之忧

C.有意识地和学校教育保持一致

D.向学校对的教育观念靠拢

E.虚心向老师请教,掌握科学的教育方法

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