问题 选择题

下列的事件:①在标准的大气压下,水加热到90℃时沸腾;②在常温下,铁熔化;③掷一枚均匀的硬币,出现正面;④实数的绝对值不小于0.其中必然事件有(  )

A.1个

B.2个

C.3个

D.4个

答案

对于①,在标准大气压下,水加热到100℃时才会沸腾

故事件“在标准大气压下,水加热到90℃时会沸腾”是不可能事件;

对于②,在常温下,铁不会熔化,故是不可能事件;

对于③,抛掷一枚硬币,可能出现正面也可能出现反面

故事件“抛掷一枚硬币,出现正面”是随机事件;

对于④,任取一个实数,它的绝对值不小于零,

故事件“实数的绝对值不小于零”是必然事件

由以上的分析可得只有④的事件是不可能事件

故选A.

多项选择题
单项选择题

For any export-oriented American business, an invitation to join the U. S. Commerce Secretary on one of his trade missions abroad is like a World Series ticket—the hottest seat in town, and something you might pay top dollar to get. In 1992, Bill Clinton promised that his Administration would fight hard to help American companies win foreign business. That’s a worthy goal of trade missions, which provide selected chief executives with priceless connections to the corporate heads and government officials of other nations.

But under the late Commerce Secretary Ron Brown were the Democrats "selling" seats, using those missions to reward party donors And did the trips serve the dual purpose of drumming up (招徕) more donations abroad Those are the questions at the heart of the lawsuit filed by the non-profit conservative group Judicial Watch Inc. Last week, thousands of pages of Commerce Department documents have been turned over to the group.

The Commerce Department papers clearly indicate many corporate contributors expected their money to earn them special consideration when seats were being handed out on the secretary’s plane. In a letter addressed to Deputy Assistant Commerce Secretary Jude Kearney, C. Payne Lucas, a development-organization executive suggests he should be added to a mission headed for South Africa president Nelson Mandela. In another, Philip Verveer, a Washington attorney, recommends a place on 1994 mission to India for William Ginsberg, chief executive of Cellular Communications International. "Oinsberg was an early financial supporter of Clinton/ Gore campaign," Verveer writes.

These missives occasionally show federal officials urging their superiors to favor donor executives. In one letter, Reta Lewis, a political affair official at the White House, urges that a spot be found for Gerald McGowan, a partner in a Washington law firm, on a trade mission to Indonesia or India. For one thing, Lewis points out, McGowan qualifies as D. N. C. "managing trustee (托管人, 理事)," someone who gives $100,000 a year to the Democratic National Committee.

But did the White House always give its funders the heavy preference they expected That is another story.

Which of the following statements is true().

A. Clinton’s Administration failed to keep his promise to help American companies win foreign business.

B. The Democrats might have taken advantage of the trade trips for more donations abroad.

C. Donor Executives long to have the honor of taking the same plane as the Commerce Secretary.

D. The Commerce Department documents clearly indicate that corporate contributors hope to finance the Secretary’s missions abroad.