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问题 选择题

下列各组中都属于被子植物的是（　　）

A．银杏、毛白杨、槟榔

B．水稻、牡丹、玉米

C．玫瑰、雪松、刺槐

D．小麦、侧柏、菊

答案

被子植物又叫绿色开花植物，主要特征是：胚珠外有子房壁包被，种子有果皮包被；受精过程不需要水，具有双受精现象；有根、茎、叶、花、果实和种子六大器官．银杏、雪松、侧柏种子裸露，没有果皮包被，属于裸子植物；毛白杨、槟榔、水稻、牡丹、玉米、玫瑰、刺槐、小麦、菊的种子外有果皮（豆荚）包被，属于被子植物．

故选B

单项选择题

Since we are social beings, the quality of our lives depends in large measure on our interpersonal relationships. One strength of the human conditions is our possibility to give and receive support from one another under stressful conditions. Social support makes up of the exchange of resources among people based on their interpersonal ties. Those of us with p support systems appear better able to deal with major life changes and daily problems. People with p social ties live longer and have better health than those without such ties. Studies over types of illnesses, from depression to heart disease, show that the presence of social support helps people defend themselves against illness, and the absence of such support makes poor health more likely.
Social support cushions stress in a number of ways. Firstly, friends, relatives and co-workers may let us know that they value us. Our self-respect is strengthened when we feel accepted by others in spite of our faults and difficulties. Secondly, other people often provide us with informational support. They help us to define and understand our problems and find solutions to them. Thirdly, we typically find social companionship supportive. Taking part in free-time activities with others helps us to meet our social needs while at the same time distracting us from our worries and troubles. Finally, other people may give us instrumental support—money aid, material resources, and needed services—that reduces stress by helping us resolve and deal with our problems.

Which of the following is closest in meaning to the underlined word "cushions"

A. takes place of


B. makes up of
C. lessens the effect of

D. gets rid of
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单项选择题

YJ29接装机水松纸切纸鼓轮沿外圆轴向镶有（）条硬质合金条。

A.16

B.12

C.17

D.18
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