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However wealthy we may be, we can never find enough hours in the day to do everything we want. Economics deals with this problem through the concept of opportunity cost, which simply refers to whether someone’s time or money could be better spent on something else.

Every hour of our time has a value. For every hour we work at one job we could quite easily be doing another, or be sleeping or watching a film. Each of these options has a different opportunity cost—namely, what they cost us in missed opportunities.

Say you intend to watch a football match but the tickets are expensive and it will take you a couple of hours to get to and from the stadium. Why not, you might reason, watch the game from home and use the leftover money and time to have dinner with friends? This—the alternative use of your cash and time—is the opportunity cost.

For economists, every decision is made by knowledge of what one must forgo—in terms of money and enjoyment—in order to take it up. By knowing precisely what you are receiving and what you are missing out on, you ought to be able to make better-informed, more reasonable decisions. Consider that most famous economic rule of all: there’s no such thing as a free lunch. Even if someone offers to take you out to lunch for free, the time you will spend in the restaurant still costs you something in terms of forgone opportunities.

Some people find the idea of opportunity cost extremely discouraging: imagine spending your entire life calculating whether your time would be better spent elsewhere doing something more profitable or enjoyable. Yet, in a sense it’s human nature to do precisely that—we assess the advantages and disadvantages of decisions all the time.

In the business world, a popular phrase is “value for money.” People want their cash to go as far as possible. However, another is fast obtaining an advantage: “value for time.” The biggest restriction on our resources is the number of hours we can devote to something, so we look to maximize the return we get on our investment of time. By reading this passage you are giving over a bit of your time which could be spent doing other activities, such as sleeping and eating. In return, however, this passage will help you to think like an economist, closely considering the opportunity cost of each of your decisions.

小题1:According to the passage, the concept of “opportunity cost” is applied to ________.

A．making more money

B．taking more opportunities

C．reducing missed opportunities

D．weighing the choice of opportunities小题2:The “leftover ... time” in Paragraph 3 probably refers to the time ________.

A．spared for watching the match at home

B．taken to have dinner with friends

C．spent on the way to and from the match

D．saved from not going to watch the match小题3:What are forgone opportunities?

A．Opportunities you forget in decision-making.

B．Opportunities you give up for better ones.

C．Opportunities you miss accidentally.

D．Opportunities you make up for.

无排卵型功血的临床表现是（）

A.月经间隔时间正常，但经期延长9～10天，量多

B.月经周期紊乱，经期长短不一，出血时多时少

C.月经周期缩短，月经频发

D.月经周期正常，量多

E.月经中期出血，量少

患儿女，14岁，因“发热，口腔溃疡，双膝关节肿痛15d，颜面皮疹3d”来诊。15d前无明显诱因出现高热，口腔多发溃疡，双膝关节肿痛。5d前于当地医院接受抗感染治疗，发热减轻。3d前颜面部出现紫红色皮疹，部分融合成片伴脱屑，脱发明显。当地考虑出现药物过敏反应，予地塞米松抗炎后皮疹较前明显好转，但融合成大片且仍低热不退，遂来诊。查体：T37.8℃，BP120/70mmHg；颜面部可见融合成片的红斑，口腔黏膜多发溃疡，最大者0.2cm×0.3cm；双肺呼吸音粗，肺底可闻及细湿性啰音；心（－），腹（－）；双膝关节无红肿及活动受限，浮髌试验（－）。实验室检查：抗核抗体、抗磷脂抗体均为强阳性，抗双链DNA（＋）。

首选治疗方案是（）

A.糖皮质激素＋免疫抑制药

B.非甾体消炎药

C.对症治疗

D.免疫抑制药

E.免疫调节药

F.抗疟药

G.生物制剂

压碎值越小，说明集料的抗压碎能力越好。

文件系统中，文件被按照名字存取是为了( )。

A．方便操作系统对信息的管理

B．方便用户的使用

C．确定文件的存取权限

D．加强对文件内容的保密