由唾液腺分泌的抗体是（）
A.IgA
B.sIgA
C.IgG
D.IgM
E.IgE
参考答案：B
解析：这些题主要是考查对各种抗体最基本的掌握，IgM是个体发育过程中最早合成和分泌的抗体，所以是天然抗体，IgM也是初次体液免疫最早出现的抗体，因此，对口腔细菌作出最初免疫应答的抗体也是IgM。IgG是血液中含量最高、作用最重要的抗体，而龈沟液主要来源于血清，所以，龈沟液中含量最高的抗体是IgG，牙周病免疫中B细胞产生的最重要的抗体也是IgG。sIgA是由唾液腺分泌的特殊的抗体。
Passage One
| Internet piracy refers to the use of the Internet for illegally copying or distributing unauthorized software. In these cases the Internet is the medium for advertising, offering, acquiring, or distributing pirated software. The Business Software Alliance, a software industry trade association, estimates that there are 840 000 Internet sites selling illegal software as genuine product. Many consumers Who acquire software over the Internet never receive the programs they paid for. Others are not able to get their money back if they discover that the software they acquired is counterfeit. Disreputable Internet businesses often quickly vanish, leaving behind hundreds of dissatisfied consumers. The ease of creating a Website and then advertising and distributing software through the Internet has increased sales of pirated software passed off by seemingly legitimate businesses. Plus, the explosive growth of e-commerce, combined with anonymity (匿名) and unlimited volume, have made it even easier for criminals to sell counterfeit (伪造的) software online. Illegal online businesses often have professional-looking Internet sites that could fool even the smartest consumer. Distinguishing counterfeit software on the Internet is understandably difficult because consumers can’t visually examine the product for physical Warnings on the hard ware, or see the person from whom they’re buying. Pirated software can often contain viruses with the potential to damage both individual com puters or entire networks. Viruses can and do cause data loss, which would be devastating to most companies. When using unlicensed software, you are not eligible for technical support from the software publisher. If you have a technical issue in need of resolution, oftentimes a work stopping issue, you are out of luck. In addition, product upgrades (升级)—less expensive up grades of existing products—are not available to you. Based on Business Software Alliance estimates, the current loss of jobs, wages, and critical investments in software and technology innovation worldwide due to piracy so far this year is estimated at: ＄11 326 675 282. "Software piracy continues unabated (不减弱的), robbing the industry of thousands of jobs, billions in wages, tax revenues and critical investments in new technologies," according to Robert Holleyman, president and CEO, Business Software Alliance. |
Internet piracy is defined as______.
A．selling pirated books over the Internet
B．stealing information from other Websites
C．copying or selling unauthorized software over the Internet
D．advertising and selling counterfeit products over the Internet