Height is just one of the thousands of 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 it out.

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

No doubt(懷疑) 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 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 or so after your body starts to show the first changes of puberty. 

(     )1. The Chinese for the word “puberty” is __________.

      A. 童年時(shí)期             B.嬰幼兒時(shí)期            C.習(xí)慣養(yǎng)成期              D. 生長(zhǎng)發(fā)育期

(     )2. 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 save the environment        

D. You can record your growth during puberty

(     )3. 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 

(     )4. After reading this passage, we can explain ___________.

A. how good it is to be a doctor                           

B. how much sleep time we need

C. why genes can’t decide everything                   

D. what healthy diet is


1.  D   2.  B   3.  D      4. C


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