题干

在一个草原生态系统中,鼠是初级消费者.现将某动物新物种X引入该生态系统,调查鼠与X的种群数量变化,结果如表.若不考虑气候和其他因素的影响,下列叙述正确的是(  )

 时间(年)

1

 2

3

 4

5

 6

7

 8

 鼠种群数量(只)

 18900

 19500

 14500

 10500

 9500

 9600

 9500

 9600

 X种群数量(只)

 100

120

 200

250

 180

170

 180

170

A:鼠和X种群为竞争关系,竞争的结果表现为相互抑制

B:客观上物种X起到促进鼠种群发展的作用,两种生物共同进化

C:引入物种X后,鼠种群的环境容纳量减小,X种群的K值是250

D:在第5年时,鼠种群的年龄组成属于衰退型

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B

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                                                                                Get a Thorough Understanding of Oneself.

    In all one's life lime it is oneself, that one spends the most time being with or dealing with.____.

    When you are going upwards in life you tend to overestimate yourself. It seems that everything you seek for is within your reach,____ It's likely that you think it wise for yourself to stay away from the outer world. Actually, to get a thorough understanding of oneself, you may as well keep the following tips in mind.

Gain a correct view of oneself.

    You may look forward hopefully to the future but be sure not to expect too much, for dreams can never be fully realized. You may be courageous to meet challenges but it should be clear to you where to direct your efforts.____

Self-appreciate.

    Whether you compare yourself to a towering tree or a blade of grass, a high mountain or a small stone, you represent a state of nature.____ If you earnestly admire yourself you'll have a real sense of self-appreciation.

____ In time of anger, do yourself a favor by releasing it in a quiet place so that you won't be hurt by its flames; in time of sadness, do yourself a favor by sharing it with your friends so as to change a bad mood into a cheerful one; in time of tiredness, do yourself a favor by getting a good sleep.

Get a full control of one's life.

    Then one will find one's life full of color and favor.

A. It has its own value.

B. Do oneself a favor when it's needed.

C. Do yourself a favor when you resist the attack of illness.

D. But it is precisely oneself that one has the least understanding of.

E. Especially if it is well within your reach, you are just too blind to see it.

F. When you are going downhill you tend to underestimate yourself for your own incompetence,

G. o long as you have a perfect knowledge of yourself, there won't be difficulties you can't overcome.