[单选题]在存货订货量决策中,下列关于保险储备的表述正确的是( )。
A.保险储备增加,存货的缺货损失提高
B.保险储备增加,存货中断的概率提高
C.保险储备增加,存货的再订货点提高
D.保险储备增加,存货的储存成本降低

The "show business" attracts many young people. (21) , only very few can hope to become (22) Talent (才能) is not (23) . Without a good manager, a performer can never hope to succeed. Fashion (时尚)is also important in this business. The best tailor in the world will never be successful if he makes old-fashioned clothes. In exactly the same way, a performer must (24) his "act" in order to (25) the taste of the moment. This is true for actors and dancers, but perhaps most of all for (26) .
"Pop" stands for "popular", and a pop singer has to (27) hard to become popular. He must either give the public what they want, or he must find a new way of singing that will attract their attention. Even when he has succeeded, and his records are sold everywhere, he cannot (28) . He must work harder than ever to (29) popular, (30) there are always younger singers trying to become fa
A. act
B. work
C. travel
D. sing

In his 1979 book, The Sinking Ark, biologist Norman Myers estimated that (1) of more than 100 human-caused extinctions occur each clay, and that one million species (2) by the century’s end. Yet there is little evidence of (3) that number of extinctions. For example, only seven species on the (4) species list have become extinct (5) the list was created in 1973.
Bio- (6) is an important value, according to many scientists. Nevertheless, the supposed mass extinction rates bandied about are (7) by multiplying (8) by improbables to get imponderables.
Many estimates, for instance, rely a great deal on a "species-area (9) ", which predicts that twice as many species will be found on 100 square miles (10) on ten square miles. The problem is that species are not distributed (11) , so bow much of a forest are destroyed may be as important as (12) .
(1
A. underplay
B. underrate
C. understate
D. undermine