Most of the flowers in nature are red, orange and yellow. If we have seen a black flower, it's chance in a million.

    People have made a survey to colors of more than four thousand kinds of flowers and discovered that only eight of them are black.

    As we know, sunlight is formed by seven colored lights. The wavelength of each light is also different, so the quantity(量) of heat in each light is also different. Flowers, especially their petals(花瓣), are easy to be harmed by high temperature.

    Black flowers can take in the light of all the wavelengths that make them dry up because of high temperature, so black flowers can hardly resist(抵抗) sunlight. But red, orange and yellow flowers can protect themselves from sunlight by reflecting(反射) the red light, orange light and yellow light, each of which has a large quantity of heat.

    We need animals. Every animal has its place in the balance(平衡) of nature. We should try to help save the animals.

    Some people think zoos are good places. The zoos give the animals the comfortable and safe living places. If the animals get hurt or ill, people will take care of them. The zoo is a good place to know the rules in the wild world. We can be much closer to nature. We can know more about the animals in the zoos by watching, listening even smelling instead of just looking at the pictures in books.

    Some people don't think animals feel happy in the zoos. Animals like pandas, wolves and bears usually live in the wild. They play and find food by themselves. They are free and happy in the wild. If they are in the zoos, food is enough and rooms are comfortable. They do not need to do their best to find food to eat or places to stay in. They just walk around, sleep day and night, but they are not free at all.

    I think we should build national parks as wild life nature reserves to protect animals. If we do nothing, animals will get fewer and fewer.