“Cool”is a word with many meanings．Its old meaning is used to express a temperature that is a little bit cold．As the world has changed，the word has had many different meanings． 
   “Cool”can be used to express feelings of interest in almost anything．
   When you see a famous car in the street，maybe you will say，“It's cool．”You may think，“He's so cool，”when you see your favourite footballer． 
   We all maximize（扩大） the meaning of“cool”．You can use it instead of many words such as “new” or “surprising”．Here's an interesting story we can use to show the way the word is used．A teacher asked her students to write about the waterfall（瀑布）they had visited．On one student's paper was Just the one sentence，“It's so cool．Maybe he thought it was the best way to show what he saw and felt． 
   But the story also shows a scarcity（缺乏）of words．Without “cool”，some people have no words to show the same meaning．So it is quite important to keep some credibility（可信性）．Can you think of many other words that make your life as colourful as the word “cool”？ I can．And I think they are also very cool．

在军事演习中，某空降兵从飞机上跳下，先做自由落体运动，在t₁时刻，速度达到最大值v₁时打开降落伞，做减速运动，在t₂时刻以较小速度v₂着地．他的速度图像如图3所示．下列关于该空降兵在0～t₁或t₁～t₂时间内的平均速度 $\overline{v}$ 结论正确的是（   ）

—Sorry, but that's the _______ one.

“国将兴，必贵师而重傅；贵师而重傅，则法度存。”当你面对老师的批评时，应该（    ）

①虚心接受，有错即改                  ②默默忍受，记恨在心

③深刻反思，鞭策自己                  ④理解老师，聆听教诲