下列零、部件平衡精度要求最高的是（）。A．精密磨床主轴  B．船用柴油机曲轴  C．

食品污染的种类按其性质可分为以下三类：____、____ 、____。

“对东印度开始进行征服和掠夺，非洲变成商业性的猎捕黑人的场所；这一切标志着资本主义生产时的曙光。这些田园诗式的过程是原始积累的主要因素。”——马克思

①结合学过的内容和上述材料概括殖民主义的罪恶。

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②怎样理解“这一切标志着资本主义生产时代的曙光”？

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③在印度进行殖民活动的是哪个国家？18世纪时号称什么？

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患者，27岁，4小时前因交通事故头部受伤，伤后有一过性意识障碍后清醒期，30分钟后再次昏迷。

若颅内压进一步增高，其瞳孔的改变最可能是（）

A.患侧瞳孔散大

B.对侧瞳孔缩小

C.患侧瞳孔缩小

D.对侧瞳孔散大

E.双侧瞳孔散大

为保证生、熟（即食）食品的隔离，下面哪项是错误的（）

A.人流：从低清洁区到高清洁区

B.水流：从高清洁区到低清洁区

C.气流：入气控制，正压排气

D.物流：从低清洁区到高清洁

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 mall 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 mall 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 mall.

Many senders of unsolicited commercial electronic mall 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 mall 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 mall cannot be solved by the government alone. The development and adoption of techno-logical approaches and the pursuit of cooperative efforts with other countries will be necessary as well.

What does unwanted e-mail messages do to the providers of the Internet services().

A. Raising their cost.

B. Raising the Internet speed.

C. Improving their business.

D. Attracting investment.