下列叙述正确的是 [ ] A.铝制容器可盛装热的H2SO4 B.Agl胶体在电场

题型:选择题

问题:

下列叙述正确的是 [ ]

A.铝制容器可盛装热的H2SO4      

B.Agl胶体在电场中自由运动

C.K与水反应比Li与水反应剧烈   

D.红磷在过量Cl2中燃烧生成PCl3

考点:铝盐(铝离子)单质铝
题型:选择题

数据要求说明书的编制处于______阶段。

A.需求分析
B.可行性研究
C.需求分析和总体设计
D.可行性研究和需求分析

题型:选择题

决定痢疾杆菌致病力的主要因素是()

A.细菌的类型

B.细菌的内毒素

C.细菌对大肠粘膜的侵袭力

D.细菌的外毒素

E.细菌的数量

题型:选择题

_____ me most was his coming to our class.

A.It surprised

B.What surprised

C.Being surprised

D.To be surprised

题型:选择题

患者清晨起床后出现右眼不能闭合,右侧眼裂较右侧大,右侧额纹消失,右侧鼻唇沟变浅,口角左歪,其病变累及()

A.侧动眼神经

B.右侧三叉神经

C.右侧大脑半球

D.右侧面神经

E.以上都不是

题型:选择题

Electronic mail has become an extremely important and popular means of communication.
The convenience and efficiency of electronic mail are threatened by the extremely rapid growth in the volume of unsolicited commercial electronic mail. Unsolicited commercial electronic mail is currently estimated to account for over half of all electronic mail traffic, up from an estimated 7 percent in 2001, and the volume continues to rise. Most of these messages are fraudulent or deceptive in one or more respects.
The receipt of unsolicited commercial electronic mail may result in costs to recipients who cannot refuse to accept such mail and who incur costs for the storage of such mail, or for the time spent accessing, reviewing, and discarding such mail, or for both. The receipt of a large number of unwanted messages also decreases the convenience of electronic mail and creates a risk that wanted electronic mail messages, both commercial and noncommercial, will be lost, overlooked, or discarded amidst the larger volume of unwanted messages, thus reducing the reliability and usefulness of electronic mail to the recipient. Some commercial electronic mail contains material that many recipients may consider vulgar or pornographic in nature.
The growth in unsolicited commercial electronic mail imposes significant monetary costs on providers of Internet access services, businesses, and educational and nonprofit institutions that carry and receive such mail, as there is a finite volume of mail that such providers, businesses, and institutions can handle without further investment in infrastructure. Many senders of unsolicited commercial electronic mail purposefully disguise the source of such mail.
Many senders of unsolicited commercial electronic mail purposefully include misleading information in the messages’ subject lines in order to induce the recipients to view the messages. While some senders of commercial electronic mail messages provide simple and reliable ways for recipients to reject (or ’opt-out’ of) receipt of commercial electronic mail from such senders in the future, other senders provide no such ’opt-out’ mechanism, or refuse to honor the requests of recipients not to receive electronic mail from such senders in the future, or both.
Many senders of bulk unsolicited commercial electronic mail use computer programs to gather large numbers of electronic mail addresses on an automated basis from Internet websites or online services where users must post their addresses in order to make full use of the website or service.
The problems associated with the rapid growth and abuse of unsolicited commercial electronic mail cannot be solved by the government alone. The development and adoption of technological approaches and the pursuit of cooperative efforts with other countries will be necessary as well.

"Opt-out" mechanism is probably ______.

A.a machine that can be attached to your computer

B.a button that you can make a choice to read or not to read

C.a software that you can play a computer game

D.an e-mail that says some good words to you

更多题库