When I was a child ,I spent most of the time near the sea watching the ships, large and small, go in and out of the harbor. At the age of eighteen I   1   home to take a job on a passenger  2   that sailed between San Francisco and YokohamA．I was   3   about my new adventure and a little afraid, too. For over a year, I    4   the Pacific on the Rosa Lee. The brilliant blue waters were   5   in the sunlight; under stormy skies the angry   6  became dark, dangerous, and exciting. I   7   the sea in all its glorious beauty — both when it was quiet and when it was violent.   8 , I knew it was the life for me.

After a year, during a rip from Melbourne to Honolulu, I had a very strange   9  . I have never forgotten it. We couldn’t get   10   the way in time and were hit by a violent 11  . The wind grew stronger and stronger —  12   fifty miles an hour, and mountains of water   13   the Rosa Lee over on its side. The ship rolled back only to be   14   again by the next wave. All during the rain-filled night, we worked in a frantic   15   to save the ship, but there was a breakdown in the engine room and the motors  16 . We knew that there was   17   more we could do. At dawn the Captain   18   the order to leave the ship. A few minutes later Rosa Lee   19   beneath the angry seA．All that could be   20    were a few lifeboats here and there among the waves.

1．A．left         B．went         C．landed        D．forgot

2．A．bus         B．ship          C．plane          D．train

3．A．worried   B．narrow       C．excited        D．sure

4．A．struck      B．imagined       C．remarked       D．sailed

5．A．shallow    B．terrifying      C．irregular        D．beautiful

6．A．situation  B．gains        C．waters         D．management

7．A．hated       B．loved        C．improved      D．greeted

8．A．In the end B．What’s more    C．That’s to say    D．From the beginning

9．A．dream      B．practice        C．imagination   D．experience

10．A．in        B．up            C．out of        D．down

11．A．purpose  B．storm         C．soul           D．rock

12．A．up to     B．far from       C．less than        D．behind

13．A．pushed   B．pulled         C．drew          D．looked

14．A．protected        B．attacked       C．destroyed      D．applied

15．A．request   B．decision        C．sense          D．attempt

16．A．worked  B．based          C．stooped        D．finished

17．A．nothing  B．space         C．light          D．recognized

18．A．gave      B．threw         C．forced         D．recognized

19．A．floated   B．sank         C．fell           D．pushed

20．A．enjoyed  B．criticized       C．seen         D．climbed

如图所示，在水平面上固定一个气缸，缸内由质量为m的活塞封闭一定质量的理想气体，活塞与缸壁间无摩擦且无漏气，活塞到气缸底距离为L₀，今有一质量也为m的重物自活塞上方h高处自由下落到活塞上并立即以碰前速度的与活塞一起向下运动，向下运动过程中活塞可达到的最大速度为v，求从活塞开始向下移动到达最大速度的过程中活塞对封闭气体做的功。(被封闭气体温度不变，外界大气压强为p₀)