问题 问答题

小明想测一小块石蜡的密度,他先用天平称出了石蜡块的质量,然后在量筒里倒入适量的水,用细线拴住石蜡块,将石蜡块放入量筒,但是他发现石蜡块不是沉入水中,而是浮在水面上.这样从量筒中水面两次到达的刻度求出的差是石蜡块的体积吗?如果不是,你能帮小明想想办法吗?你能想出几种方法?

答案

答:

石蜡块浮在水面上时,从量筒中水面两次到达的刻度求出的差,是石蜡排开水的体积,不是石蜡块的体积;

要使石蜡排开水的体积等于石蜡块的体积,可以采用:

①“上压法”,用细针将石蜡快按入水面以下,记下体积;

②“下坠法”,用细线将石蜡块和铁块连在一起,将蜡块拉入水面以下;

③“捆绑法”,用细线将石蜡块和铁块绑在一起,共同浸没在水面以下.

解答题
单项选择题

On the ground floor of the Federal Reserve building in Washington, DC, there is an electronic game which tests a visitor’s skill at setting interest rates. You have to decide how to respond to events such as rising inflation or a stockmarket crash. If you get all the answers right, the machine declares you the next Fed chairman. In real life, because of huge uncertainties about data and how the economy works, there is no obviously right answer to the question of when to change interest rates. Nor is there any easy test of who will make the best Fed chairman. So who would The Economist select for the job

Alan Greenspan will retire as Fed chairman on January 31st, after a mere 181/2 years in the job. So George Bush needs to nominate a successor soon. Mr. Bush has a penchant for picking his pals to fill top jobs: last week he nominated his personal lawyer Harriet Miers to the Supreme Court. But his personal bank manager really would not cut the mustard as Fed chairman. This is the most important economic-policy job in America—indeed in the whole world. The Fed chairman sets interest rates with the aim of controlling inflation, which in turn helps determine the value of the dollar, the world’s main reserve currency. It is hardly surprising that financial markets worldwide can rise or fall on his every word.

Financial markets are typically more volatile during the first year after the handover to a new chairman than during the rest of his tenure. In October 1987,barely two months after Mr. Greenspan took office, the stock market crashed. Current conditions for a handover are hardly ideal. America’s economy has never looked so unbalanced, with a negative household savings rate, a housing bubble, a hefty budget deficit, a record current-account deficit and rising inflation. Figures due on October 14th are expected to show that the 12-monthrate of inflation has risen above 4% —its highest since 1991.

Which of the following, according to the text, is a common phenomenon()

A. Financial markets and stock markets crash due to the handover

B. Comment by the Fed chairman are invalid in the world financial markets

C. Inflation rises above 4% —record high level

D. Remarks by the Fed chairman can sway the world financial markets