问题 问答题 简答题

座环的作用是什么?

答案

参考答案:

是承受整个机组及其上部混泥土的重量以及水轮机的轴向水推力,以最小的水力损失将水流引入导水机构,机组安装时以它为基准,所以既是过流部件、又是承重件、也是基准件。座环由上下环和固定导叶三大部件组成。

选择题
单项选择题

Until the late 1940s, when television began finding its way into American homes, companies relied mainly on print and radio to promote their products and services. The advent of television (1) a revolution in product and service. Between 1949 and 1951, advertising on television grew 960 percent. Today the Internet is once again (2) promotion. By going online, companies can communicate instantly and directly with prospective customers. (3) on the World Wide Web includes advertising, sponsorships, and sales promotions (4) sweepstakes, contests, coupons, and rebates. In 1996 World Wide Web advertising revenues (5) $ 300 million.

Effective online marketers don’t (6) transfer hard-copy ads to cyberspace. (7) sites blend promotional and non-promotional information indirectly delivering the advertising messages. To (8) visits to their sites and to create and (9) customer loyalty, companies change information frequently and provide many opportunities for (10) .

A prototype for excellent (11) promotion is the Ragu Web site. Here visitors can find thirty-six pasta recipes, take Italian lessons, and view an Italian film festival, (12) they will find no traditional ads. (13) subtle is the mix of product and promotion that visitors hardly know an advertising message has been (14) . Sega of America, maker of computer games and hardware, uses its Web site for a (15) of different promotions, such as (16) new game characters to the public and supplying Web surfers the opportunity to (17) games. Sega’s home page averages 250,000 visits a day. To heighten interest in the site, Sega bought an advertising banner on Netscape (18) increasing site visits by 15 percent. Online (19) in Quaker Oats’ Gatorade promotion received a free T-shirt in exchange for answering a few questions. Quaker Oats reports that the online promotion created product (20) and helped the company know its customers better.

5()

A.arrived

B.topped

C.overcame

D.descended