体积为5m³的水，在温度不变的情况下，当压强从1at增加到5at时，体积减少1升，则水的压缩系数为（）。

A. 5.1×10^-10m²/N

B. 5.1×10^-9m²/N

C. 3.4×10^-10m²/N

D. 3.4×10^-9m²/N

The swan is mostly silent through its life, unable to sing sweet songs like most other birds. In ancient times, however, people believed a swan sings a most beautiful song just before it dies. The ancient Greek philosopher Socrates talked of this 2,300 years ago. Socrates explained that the swan was singing because it was happy. The bird was happy because it was going to, serve the Greek God Apollo. Swans were holy to Apollo, the god of poetry and song.
The story of the swan’s last song found a place in the works of other writers, including the early English writers Chaucer and Shakespeare. And the expression swan song has long been a part of the English language. At first, "swan song" meant the last work of a poet, musician or writer. Now, it means the final effort of any person. Someone’s swan song usually is also considered that person’s finest work.
A political expression with a similar meaning is "the last hurrah". The expression may be used to describe a politician’s last campaign, his final attempt to win cheers and votes. The last hurrah also can mean the last acts of a politician, before his term in office ends. Writer Edwin O’Connor made the expression popular in 1956. He wrote a book about the final years in the political life of a long-time mayor of Boston. He called his book The Last Hurrah.
Some language experts say the expression came from a name given to noisy supporters of Andrew Jackson, America’s seventh president. They cheered hurrah so loudly for Andy Jackson during his presidential campaign that they became known as the hurrah boys.
Jackson’s hurrah boys also played a part in the election to choose the next president. Jackson’s choice was his vice president, Martin VanBuren. A newspaper of the time reported that VanBuren was elected president: "... by the hurrah boys, and those who knew just enough to shout hurrah for Jackson. " President Jackson really heard his last hurrahs in the campaign of the man who would replace him in the White House.

President Jackson’s last hurrah was to ______.

A. express his gratitude to his supporters
B. win the final cheers from his supporters
C. defeat another candidate in the election
D. help his vice president get elected