共享单车是城市慢行系统的一种模式创新，对于解决民众出行“最后一公里”的问题特别见效，由于停取方便、租用价格低廉，各色共享单车受到人们的热捧．某自行车厂为共享单车公司生产新样式的单车，已知生产新样式单车的固定成本为20000元，每生产一件新样式单车需要增加投入100元．根据初步测算，自行车厂的总收益（单位：元）满足分段函数h（x），其中 $h\left(x\right)=\{\begin{array}{c}400x-\frac{1}{2}{x}^2，0<x\le 400\\ 80000，x>400\end{array}$ x是新样式单车的月产量（单位：件），利润=总收益﹣总成本．

将一个圆柱体的侧面展开，得到一个正方形，圆柱的底面半径是5厘米，圆柱的高是____厘米。

      We can make mistakes at any age. Some mistakes we make are about money. But most mistakes are about people.
Why do we go wrong about our friends? Sometimes people hide their real meanings when they say something. And if we don't really listen, we miss the feeling behind the words. Suppose someone tells you, “You're a lucky dog.” That's being friendly. But “lucky dog”? There's a bit of envy(嫉妒) in those words. Maybe he doesn't see _it_ himself. But “lucky dog” puts you down a little. He may mean you don't deserve your luck.
      How can you tell the real meaning behind someone's words? One way is to take a good look at the person talking. Do his words fit the way he looks? Do his words agree with the tone(语调) of voice? His posture(姿态)? The look in his eyes? Stop and think. If you spend the minute thinking about the real meaning behind one's words, it may save another mistake.

阅读理解

    YOUTR KIDS ARE AMAZING -especially compared with everybody else s (who seem to cry all the time). How do you show your love for your kids this holiday season? With toys that are smooth and colorful, interactive and exciting. And with ones that have educational value - because you are the boss.

FLAX ART HOSPITAL PUZZLE AND PLAY SET

    Here is a toy that doesn't need power, and the kids have to put it together themselves. This 50*piece-puzzle set is made of soft-edged hardwood and makes a complete hospital, with an X-ray room. It also includes eight patients, a car and a driver. $135; flaxart.com.

    TINY LOVE ACTIVITY BALL

    Sure, it's cool, but this colorful baby toy also develops problem solving and motor skills. It has a head and legs, a magnetic (磁铁) hand and a tail. Suitable for little ones from 6-36 months. $19.95; tiny-love.com.

    ROBOSAPIEN

    This small, remote-control robot is really powerful. It performs 67 preprogrammed functions, including throwing, kicking, picking up and dancing. You can even program your own function - which, sadly, does not include doing windows. $ 99; robosapienonline.com.

    MINI PEDAL CAR

    Want a mini Cooper but can't fit the family inside? Get one for the kids. They can jump into this mini car, which comes in hot orange with a single adjustable seat, and ride away. But it could spoil them for that used car they'll be driving when they turn 16. For ages 3 to 5. $ 189; mlnicar.com (click on “gear up” then “mini motoring gear”）

利用下图所示装置，探究可燃物的燃烧条件。

已知：白磷的着火点为40℃