Height is just one of the thousands of features your genes decide. In fact, because you have two parents, your genes provide you a height that usually lands somewhere between the height of each parent. If both your parents are tall, then most probably you will be tall, too, but if you have questions about how tall you're going to be, ask your doctor if he or she can help you find it out.

    But genes don't decide everything. For example, eating an unhealthy diet can keep you from growing to your full potential(潜力). Getting plenty of sleep and enough exercise will help you grow to the expected height.

    No doubt you're wondering how fast you should grow. It depends. There's no perfect or right answer. Generally speaking, kids grow about 2 inches (6 centimeters) a year between age 3 and the time when they start puberty (when your body starts changing and becoming more grown up).

    Your doctor will know how your growth has been going over the years. Two centimeters here and 2 inches there are not nearly as important as the height you're at now, how you've been growing up to this point, and what other changes your body may be going through.

    Don't be scared if you seem to have grown a lot in a very short time. Everyone has a growth spurt（高峰）during____The age for starting puberty is about 10 for girls and about 11 for boys. But it can be earlier or later —between 7 and 13 for girls and 9 and 15 for boys.

    You'll usually begin to notice that you're growing faster about a year or so after your body starts to show the first changes of puberty.

    If you go shopping in any toy store, you can see clearly the differentgames and toys for boys and girls: there are a lot of pink toys on one side ofthe store for girls; and dark colored cars, guns, and soldiers for boys. Somebig stores with toys may even have a pink floor for girls and a blue floor forboys. In fact, it is difficult to buy a toy for a girl that is not pink.

    Somepeople think that too much pink is bad for girls. Sue Palmer, writer of ToxicChildhood, is very worried that most girls over the age of three are crazyabout the color. According to some scientists, this happens for two reasons. Firstly,most companies offer too many products in pink. Also, many parents think theirlittle daughter looks cute in pink. Sue Palmer says that girls at this agecannot make proper decisions by themselves, but the pink can affect (影响) the choices and thedecisions they will make in the future.

    Someparents are worried too-for example, Vanessa Holburn, thirty-two, who has twogirls under the age of four. Their bedrooms are a sea of pink and Vanessa isnot happy. "Pink says that you are soft and gentle. Blue says that you arestrong and powerful. I want my daughters to be strong and powerful. I'm worriedthat pink will not help them with that,"she says.

    Butnot everyone thinks there's something wrong with pink. Grayson Turner is afather of three girls and he isn't worried at all. "People forget thatthings change all the time," he says. "My girls used to love pink whenthey were little, but as they get older, they change." Turner explainsthat his twelve-year-old daughter never wears pink clothes anymore. "Thislove of pink is just a fashion and all fashions change," he adds. "It'sonly since the 1940s that people have started dressing girls in pink-beforethat it was a color for boys."

    Humans can go to the hospital when they're ill. But as for animals, what should they do？To stay healthy, animals have their own ways to heal(治愈)themselves. Now let's get to know their special skills.

    Skill One

    Have you ever seen your dog or cat lick(舔)its wounds？Why do they do it？It probably feels good, but it's good medicine. Licking cleans a wound, and saliva(唾液)has chemicals that kill germs(细菌).

    Skill Two

    To avoid diseases, many animals have good living habits. They hate to be dirty. Most animals separate their pooping(排便)areas from their eating areas. Horses poop far away from the grass they eat. Rabbits put their poop in special pooping areas.

    Skill Three

    Have you ever heard of the expression "starve a fever(发烧时宜饿)"？Many animals stop eating when they're ill. When a sick animal stops eating, it can stop germs from getting necessary things.

    Skill Four

    Another way that animals heal themselves is to raise their body temperature. High temperature can kill germs. Warm—blooded animals(like us)get fevers to fight with germs.

    Cold—blooded animals(like snakes)look for pieces of wood or rocks heated by the sun.

    Fish move to warmer waters.

    When the Audet family turns on the lights at Blue Farm, they are using electricity that comes from cows- cow manure(粪肥).

    Cows produce a lot of waste. One cow can create 30 gallons of waste each day. Now imagine the output of over 1,000 cows at Blue Farm. That's really a big amount.

    When farmers clean their barns, they put the waste together，and spread some of it on their fields for fertilizer(肥料). But now places like Blue Farm have a new way of using cow waste. They use it to produce electricity.

    Here's how it works: A big machine moves back and forth cleaning the barn floor. "The cows are animals of habit; they get used to it,and just lift one foot and then another to let it go by. "says Marie Audet.

    The machine pushes the manure into a big 600-gallon tank like a small swimming pool. The tank is called a digester(化粪池) because what happens there is just like what happens inside a cow: Bacteria(细菌) get to work and continue to digest the manure.

    Methane gas(甲烷;沼气) in the atmosphere is known as a "greenhouse" gas because it keeps heat just like a greenhouse does, causing our planet to warm up. That's an environmental concern. But the digester has a good result. Its gas is kept and used to power electric generators(发电机).

    At Blue Farm, the generators make enough electricity to power 400 homes. The Audet family sells the extra electricity they can't use themselves.

    Charlie and his family don't always live in their house. Sometimes they live in a houseboat. There are 4 rooms in the bottom of the boat. One of them is his parents' bedroom. Another one is his bedroom. Then there is a kitchen and a bathroom. Charlie's bedroom is small, but he likes it very much. It has a small window. He doesn't open it because it's under the water. When the boat is in the water, Charlie can look out of his window and see many fish under the water. Once he saw an old car under the water. He thought it was funny to see the fish swim through the car windows.

    In the school year, Charlie's family keep their boat on the bank (岸) of the lake. In summer Charlie and his family often take their boat out to the middle of the lake. They stay on the lake for a few weeks. Then they go fishing for their food. Charlie's mother grows vegetables in pots on the boat, so they also have vegetables to eat. When it is very hot, they jump into the water and go swimming. Charlie thinks a houseboat is the best place to live in.