经典途径的C5转化酶是（） A．C（C4b2b3b） B．C C．C 2b3b D．

一个直角三角形两条直角边相等，这样的三角形又叫（    ）三角形，它的一个底角是（    ）^。。 

如题17图所示的电容式话筒就是一种电容式传感器，其原理是：导电性振动膜片与固定电极构成了一个电容器，当振动膜片在声压的作用下振动时，两个电极之间的电容发生变化，电路中电流随之变化，这样声信号就变成了电信号．则当振动膜片向左振动时，以下说法中正确的是

①电容器电容值增大

②电容器带电荷量减小

③电容器两极板间的场强增大

④电阻R上电流方向自左向右

A．①③

B．①④

C．②③

D．②④

图中两条平行虚线之间存在匀强磁场，虚线间的距离为l，磁场方向垂直纸面向里,abcd是位于纸面内的梯形线圈，ad与bc间的距离也为l.t=0时刻，bc边与磁场区域边界重合（如图）.现令线圈以恒定的速度v沿垂直于磁场区域边界的方向穿过磁场区域.取沿a→b→c→d→a的感应电流为正，则在线圈穿越磁场区域的过程中，感应电流I随时间t变化的图线可能是(    )

国家对烟草专卖品的生产、销售、运输依法实行专卖管理，并实行烟草专卖许可证制度。

People in the mass advertising business and others who study American society have been very interested in the question: What does the American consumer like Max Lerner, a well-known scholar who has studied American society, has said that American consumers are particularly fond of three things: comfort, cleanliness, and novelty.

Lerner believes that the American love of comfort perhaps goes back to the frontier experience, where life was tough and there were very few comforts. This experience may have created a p desire in the pioneers and their children for goods that would make life more comfortable. Today, the American’s love of comfort is seen in the way they furnish their homes, design their cars, and travel. How Americans choose a new mattress for their bed is an example of the Americans love of comfort. Many Americans will go to a store where beds are set up, and they will lie down on several mattresses to see which one is the most comfortable.

Cleanliness is also highly valued by Americans. There is a p emphasis on keeping all parts of the body clean, and Americans see lots of TV commercials for soap. shampoo, deodorants, and mouthwash. Perhaps the Puritan (清教徒的) heritage has played some role in the desire for cleanliness. The Puritans, a strict Protestant (新教的) church group who were among the first settlers of America, stressed the need to cleanse the body of dirt and of all evil tendencies, such as sexual desire. The saying "Cleanliness is next to Godliness" reflects the belief of most Americans that it is important to keep not only their bodies, but also their clothes, their houses, their cars, and even their pets clean and smelling good. Indeed, many Americans are offended by anyone who does not follow their accepted standards of cleanliness.

Along with cleanliness and comfort, Americans love having things that are new and different. Perhaps this love of novelty comes from their pride in their inventiveness. American have always been interested in inventing new products and improving old ones. They like to see changes in cars, clothing, and products for the home. Advertisements encourage people to get rid of old products and try new ones, whether the old ones still work or not. And if they cannot afford to buy something now, advertisers encourage consumers to charge it on a credit card. "Buy now-pay later. \

Which of the following words is NOT appropriate to describe Americans, according to the passage（）。

A. Tidy.

B. Inventive.

C. Conservative.

D. Clean.