问题 单项选择题

下列说法中,正确的是______。

A.Java语言是以类为程序的基本单位的

B.Java语言是不区分大小写的

C.多行注释语句必须以“∥”开始

D.在Java语言中,类的源文件名和这个类的类名可以不相同

答案

参考答案:A

解析: Java语言是区分大小写的,这是它与C语言的不同之处。所以B的说法是错误的;以“∥”开始的是单行注释,而多行注释要用“/*…*/”或“/**…*/”,所以选项C不正确;Java程序源文件名必须和public类名相同,否则编译将会出错,因此选项D不正确。

多项选择题
单项选择题

Even plants can run a fever, especially when they are under attack by insects or disease. But (1) humans, plants can have their temperature (2) from 3,000 feet away—straight up. A decade ago, (3) the infrared scanning technology developed for military purpose and other satellites, physicist Stephen Paley (4) a quick way to take the temperature of crops to determine (5) ones are under stress. The goal was to let farmer (6) target pesticide spraying (7) rain poison on a whole field, which (8) include plants that don’t have the pest problem.

Even better, Paley’s Remote Scanning Services Company could detect crop problem before they became (9) to the eye. Mounted on a plane flown at 3,000 feet (10) , an infrared scanner measured the heat emitted by crops. The data were (11) into a color-coded map showing (12) plants were running "fevers". Farmers could then spot spray, using 50 to 70 percent less pesticide than they (13) would.

The bad news is that Paley’s company closed down in 1984, after only three years. Farmers (14) the new technology and long-term backers were hard (15) . But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to (16) into operation. Agriculture experts have no doubt about the technology works. "This technique can be used (17) 75 percent of agricultural land in the United States," says George Oerther of Texas A&M. Ray Jackson, who recently retired from the Department of Agriculture, thinks (18) infrared crop scanning could be adopted by the end of the decade. But (19) Paley finds the financial backing (20) he failed to obtain 10 years ago.

19()

A. even if

B. if only

C. only if

D. though