专门的关系运算中，对单个关系进行垂直分解的是 ______。

按SHELL设计EO优级产品中二氧化碳含量控制在（）ppm（wt）以下。

A、50

B、30

C、20

D、10

下列各句中，没有语病的一句是(　　 ) （3分）

A．凡事若不问青红皂白，把自己心中的愤怒发泄到臆想对象身上，很可能造成对毫不知情的或有恩于己的善良的人遭到伤害。

B．她的创新设计投入生产仅三个月，就为公司带来了丰厚的利润，为这项设计付出的所有努力和取得的成绩终于得到了回报。

C．欧债危机爆发之后，欧洲现在面临的最大困境是如何解决失业问题，严峻的形势将巨大的挑战带给了欧洲各国的经济复苏。

D．哈佛燕京图书馆每年都有一次卖旧书的盛会，每次我都能在一堆堆五花八门的书里淘到如金子般珍贵的书，并因此而兴奋。

胎儿一手脱出 * * ，能与检查者右手相握，胎头位于母体腹部左侧，其胎位是（）

A.肩左前

B.肩左后

C.肩右前

D.肩右后

E.肩左横

七点法面积井网的注水强度较低，最终采收率也较低。

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