SECTION C

Directions: Complete the following passage by filling in each blank with one word that best fits the context.

Baby survives after train hits pram

The CCTV footage (片段）shows a baby’s pram (婴儿车)rolling off a train platform as the mother makes a mad rush to save her son,   48   she is too late and it falls   49   the rails in front of an incoming train. This heart-stopping scene happened yesterday at Ashburton station in Melbourne, Australia. But the story has a   50   ending: the six-month-old baby survived with just   51   cut on his forehead, although the pram was dragged about 35 meters by the braking train. The nurse Jon Wright said the boy just “needed a feed and a sleep”.

“Luckily, he was strapped (绑) into his pram at the time, which probably saved   52  life. I think the child is extremely   53  ,” Wright told the Herald Sun newspaper after the baby was taken to hospital with minor injuries. The footage shows the mother taking her hands off the three-wheeled pram, which begins to roll   54 the platform edge. 

The driver put on the brakes   55   he saw the pram fall in front of him and fortunately the train was already slowing down to stop at the station. Rail firm Connex is to look into how the pram rolled off the platform. The accident came one day after Connex started a child safety awareness campaign warning parents to keep babies strapped into their prams at all times while on platforms.

一升降机在箱底装有若干个弹簧，设在某次事故中，升降机吊索在空中断裂，忽略摩擦力，则升降机在从弹簧下端触地后直到最低点的一段运动过程中（　　）

A．升降机的速度不断减小

B．升降机的加速度不断变大

C．先是弹力做的负功小于重力做的正功，然后是弹力做的负功大于重力做的正功

D．到最低点时，升降机加速度的值一定大于重力加速度的值