问题 单项选择题

太空垃圾,主要由滞留在太空的废弃卫星和火箭残体(又称空间碎片)构成,还包括天然流星体。它们不仅对地面的人类造成危害,还威胁到在太空中飞行的航天器的安全。

有没有办法清除掉太空垃圾呢?经过多年的研究探索,科学家们已经找出了一些清除太空垃圾的方法。

美国航空航天局正在试验一种“激光扫帚”,它主要针对直径1—10厘米的太空垃圾。“激光扫帚”锁定某个太空垃圾目标后,将发出一束激光,照射在太空垃圾背离地球的一端,使之部分升华为气体,就像喷气式飞机的原理一样,利用气体的反作用力推动太空垃圾朝地球的方向运动,最终使其进入大气层,与大气层产生强烈摩擦而燃烧自毁。

英国科学家发明了一种专门清理大型太空垃圾的人造“自杀卫星”。这种自杀式卫星体积只有足球那么大,重6公斤,制造和发射的全部费用不到100万美元。它配备4台小型摄像机,能十分容易地发现太空垃圾。它一旦侦察到太空垃圾,便依附在垃圾上,使其速度降低,最后进入大气层,与太空垃圾同归于尽。

目前,人们把上述这类工具形象地统称为“太空清洁工”。虽然这类工具多数还处于试验阶段,但相信随着技术的进步和环保意识的提高,在不久的将来,太空垃圾问题将逐步得到缓解。

 

关于人造“自杀卫星”,哪一项是错误的?()

A.用来清理大型太空垃圾 

B.体积很小,只有足球那么大 

C.配备了摄像机,容易寻找太空垃圾 

D.能够依附在太空垃圾上,降低速度

答案

参考答案:D

解析:

短文说“它一旦侦察到太空垃圾,便依附在垃圾上,使其速度降低”,说明降低的是太空垃圾的速度,不是自身的速度。所以选D。

解答题
单项选择题

One day, a poor boy who was selling goods from door to door to pay his way through school found he had only one thin dime left, and he was hungry. He decided he would ask for a meal at the next house. However, he lost his nerve when a lovely young woman opened the door. Instead of a meal he asked for a drink of water. She thought he looked hungry so she brought him a large glass of milk. He drank it slowly, and then asked, "How much do I owe you" "You don’t owe me anything," she replied. He said, "Then I thank you from my heart. ’
Years later that young woman became critically iii. The local doctors sent her to the big city, where they called in specialists to study her rare disease. Dr. Howard Kelly was called in for the consultation. When he heard the name of the town she came from, he rose immediately and ’went to her room. Dressed in his doctor’s gown he went in to see her. He recognized her at once. He went back to the consultation room determined to do his best to save her life. From that day he gave special attention to the case. After a long struggle, the battle was won.
Dr. Kelly requested the business office to pass the final bill to him for approval. He looked at it and then wrote something on the edge. The bill was sent to her room. She feared to open it, for she was sure it would take the rest of her life to pay for it all. Finally she looked, and something caught her attention on the side of the bill. She read these words: "Paid in full with one glass of milk.\

Among other things, the story shows that______.

A.good will be rewarded with good

B.it is okay to accept pay for a kindness

C.it is wise neither to borrow nor to lend

D.where there’s a will there’s a way