Height is just one of the features your genes(基因) 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 them 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.

    It's natural that you're wondering how fast you should grow. There's no perfect or right answer. Generally speaking, kids grow about 6 cm a year between age 3 and the time when they start puberty.

    Your doctor will know how your growth has been going over the years. 2 cm here and 3 cm there make a little difference to the height you're at now. How have you been growing up to this height? What other changes may your body be going through?

    Don't be amazed if you seem to have grown a lot in a very short time. Everyone has a growth spurt(高峰) during puberty. 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 after your body starts to show the first changes of puberty.

根据材料内容选择最佳答案。

    Since the beginning of history, man has been fascinated by the idea of living forever, of winning the fight against death and disease. So far, this has only remained a dream, though a very powerful one. Many people have wondered whether it would be possible to find a way to preserve human bodies, and what would be the best way to preserve human bodies.

    It has long been known that meat or fruit can be kept fresh for long periods by freezing; in ancient China, for example, food was stored with ice to keep it fresh. This method could also be useful for preserving humans, and in fact many people have explored this possibility.

    However, most living beings that exist under warm conditions die when frozen. This is because of the harmful effects of freezing ice crystals, which are not only larger than the volume of the water originally in the cells, but also form sharp cutting shapes that harm the cells.

    In the 1940s Dr B. J. Luyet and a group of scientists in England were working on the problem of freezing cells without damaging them. Since the harm caused by ice crystals was the main cause of the damage, Luyet suggested removing some or all of the water from the cells before freezing them.

    Using living cells from chicken, Luyet and his assistants discovered that they could partly dry the chicken cells, using a mixture of the white part of an egg and glycerin, a clear thick liquid made chiefly from fats and oils. Some success was obtained. The chicken cells were dried, frozen for a period of time, and then carefully unfrozen.

    Almost all the cells recovered when they reached normal temperature. Since then, the cooling of whole animals to a temperature very much below freezing point for later unfreezing has become more of a possibility, and the glycerin method would probably be used to accomplish this. When this can be done completely and successfully, science will have moved much closer to its aim of freezing and storing incurable patients until the day they can be cured.

Do you want to get your heart pumping？The following movies are coming to make your summer vacation exciting？

If these movies can't interest you，you can also watch some others like Chang An. Never Say Never，Creation of The Gods I. 

When I was about fourteen , I had a lot of freckles(雀斑). I was so upset. I tried different ways to cover the freckles, but my mother would shake her head and say ,"▲"I felt sad hearing it .

My cousin Jessica had a peaches and cream complexion(白里透红的肤色) I couldn't help thinking that my life would be a lot different if I had a beautiful face too.

And then, in a magazine I found an advertisement(广告) for a freckle removal cream(祛斑霜) knew that I could afford it if I saved my money and I did . For three weeks I went to the mailbox every day exactly at the time the mail arrived.

Finally, I got the magical cream and I couldn't wait to try it on my face . Later that day I went to work on the farm. But if you apply it in the sun, it seems to make your skin worse. Instead of developing a clear complexion, you just get more and darker freckles.

By the end the day when I came back to the house, my family began to say things like," I have never seen you with that many freckles "When I saw myself in the mirror, I cried and hid in the bathroom .

When my grandfather came to see what was wrong with me I told him about the story of the freckle removal cream. Grandpa didn't understand, so I tried to explain why I didn't want to have freckles . He looked at me in surprise and said, "But my child, there are all kinds of flowers, and they are all beautiful." I said," I have never seen a flower with freckles ! "Then I ran back to my room.

When I opened my eyes the next morning, the first thing I saw was a tiger lily—a beautiful flower with freckles. I didn't know where Grandpa found it. Looking at it , I was lost in thought ...

Taking public transportation（公共交通） in the United States, you can often see people reading books on their way to school or work. But in China, I rarely （很少的） see people reading during their free time. 

Are people's attitudes toward reading different here？Not really, Data （数据） released by Amazon China in December 2017 show that Chinese people still read a lot. They simply prefer e﹣books over regular books. 

However, other data show that reading is still more popular in the US than in China. Is there a reason for this difference？I'm not sure. What I do know is that China has a rich history of literature （文学） （From classic novels like Romance of the Three Kingdoms（《三国演义》） to the modern science﹣fiction books The Three﹣ Body Problem（《三体》）, Chinese writers have created many fantastic written works. Perhaps the difference starts from childhood. Reading textbooks and doing homework can make you feel quite tired. By the time you finish it, you might not fell like reading for fun. Chinese students definitely （肯定） have to read more and do more homework than US students. So it's no wonder that they might not want to read much in their spare time. 

But learning to love reading can be great. Reading can open doors to places, people and ideas that you cannot imagine. Even just a single book has the power to change your own beliefs and attitudes. Where will your next book take you?

We can use the computer to do a lot of things on the Internet. When do my classmates go online? And what do they often do on the Internet? Now, let's have a look!