Height is just one of the thousands of features (特征) that 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 maybe 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 enough sleep and enough exercise will help you grow to the right height.
No doubt you’re wondering how fast you should grow. There’s no perfect or right answer. Kids grow about 2 inches (5 centimetres) 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 centimetres 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 very quick growth 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, 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.
The Chinese for the underlined word in the third paragraph “puberty” is           .

A．童年时期

B．婴幼儿时期

C．习惯养成期

D．青春期

If you want to know how fast and how tall you should grow,          .

A．you should have enough exercise

B．you can ask doctors for help

C．you should protect the environment

D．you can record your growth during puberty

This passage is mainly about            .

A．how the genes work in your body

B．when is the time you grow fast

C．why you look like your parents

D．how you grow to a certain height

After reading this passage, we can explain ___________.   

A．how good it is to be a doctor

B．how much sleep we need

C．why genes can’t decide everything

D．what an unhealthy diet is

Which is NOT mentioned (提及) in the passage?

A．Your height most probably depends on (取决于) how tall your parents are.

B．Girls’ age for starting puberty is usually earlier than that for boys’.

C．The time showing the first changes of puberty is never noticed.

D．You may be scared sometimes when you grow too fast.