问题 问答题 简答题

试述狗的生活习性。

答案

参考答案:

①等级性:犬生性好群居,群体中有明显的等级制度。在犬饲养场、农村或城郊的犬群中,总有一条头犬(通常是老犬)支配、管辖着犬群。

②好与人交往:与人交往是犬天生的习性,但其程度常取决于3-7周龄时与人接触“印记”的程度。

③强烈的领域观:犬和其他动物(如猫科动物、鸟类和啮齿类动物)一样,都有领地感,它以自己为中心,用自己的气味标出地界。并经常更新。

④嗅闻的习性:犬最重要的感觉是嗅觉,它们通过互相嗅闻最能反映情感的外生殖器部位(这个部位的皮腺能分泌出对犬有极大诱惑力的气味),就可辨别该犬的性别、年龄、身体状况及其态度。

⑤喜欢爬跨:各种年龄、性别的犬都有爬跨的行为,但其目的和表现都不一样。⑥超感觉机能:超感觉,强嗅觉,耳听八方,近视眼,味觉迟钝。

⑦其他特性:忠于主人,智力发达,天生胆小,归家本领,表情丰富

选择题
阅读理解

阅读理解。

      Cancer is feared by everyone. And there is more and more fear about cancer. Not the disease

itself - there is no such thing as a high incidence rates(发病率) of cancer. Except for lung cancer,

mostly caused by cigarette smoking, the incidence rates are not on the rise. However, some kinds

of cancer are decreasing. But the fear of cancer is catching, and the country stands at risk of an

anxiety. The earth itself is coming to seem like a huge carcinogen(致癌物). The ordinary, more or

less, scientific statement that something between 80 and 90 percent of all cancers are due to things

in the environment is taken to mean that none of us will be safe until the whole environment is "cleaned

up." This is not at all the meaning.

     The 80-percent calculation is based on the unthinkable differences in the incidence of cancer in

various societies around the world - for example, the high incidence of liver cancer in Africa and

the Far East, stomach cancer in Japan, breast cancer in Western Europe and North America, and

the relatively low figures for breast cancer in Japan and parts of Africa and for liver cancer in America.

These data show there may be specific environmental influences, but largely based on personal life-style,

which determines the incidence of various forms of cancer in different communities - that is all the

data suggest. The overall incidence of cancer, counting up all the cases, is probable roughly the same

everywhere.

1. According to the passage, the incidence of cancer is generally believed _____.

A. to be based on inactive life style

B. to be due to anxiety

C. to result from environmental influences

D. to be caused by heavy smoking

2. It can be inferred from the passage that the writer's opinion about the relationship between cancer

    and environment is _____.

A. positive

B. negative

C. neutral

D. approving

3. According to the passage, the writer seems to feel that _____.

A. the risk of catching cancer is on the rise

B. the whole earth is coming to seem like a huge carcinogen

C. the risk of catching cancer isn't so great as people think

D. cancer can be cured if the environment is cleaned up

4. Which of the following would be the best title for the passage?

A. Cancer and Environment

B. The Fear Caused by Cancers

C. Data on Cancer Incidence

D. Cancer and its Investigation