关于感染导致脓胸，叙述正确的有（） A.肺部感染和胸腔操作是导致脓胸产生的主要原因

关于债券投资风险及其规避的论述，不正确的是( )。

A．购买国债一般没有违约风险和变现力风险

B．购买国债仍可能遇到利率风险、再投资风险和购买力风险

C．债券投资主要面临违约风险、利率风险、购买力风险、变现力风险和再投资风险、

D．购买即将到期的优质长期债券可避免利率风险、变现力风险和再投资风险

小明所设计的“估测大气压的值”的实验方案如下：

(1)把注射器的活塞推至注射器筒的底端，然后用—个橡皮帽封住注射器的小孔；

(2)如图9所示，用细尼龙绳拴住注射器活塞的颈部，使绳的另一端与固定在墙上的弹簧测力计的挂钩相连，然后水平向右慢慢地拉动注射器筒.。当注射器中的活塞刚开始移动时，记下弹簧测力计的示数F； 

(3)观察并记录注射器筒上所标明的容积V，用刻度尺测出注射器的全部刻度长度L。

①根据以上实验方案，用测得和记录的物理量计算大气压强的表达式p=                。

②按照上述实验方案，若测得的大气压强的值比实际值偏小，你认为可能的原因是_   _____。

③按照上述实验方案，若测得的大气压强的值比实际值偏大，你认为可能的原因是___  ___。 

()认为员工的知识是“投入”，员工的行为是“转化”员工满意度和绩效是“产出”。

A.一般系统理论

B.行为角色理论

C.人力资本理论

D.交易成本理论

Internet shopping is a new way of shopping. Nowadays, you can shop for just about anything from your armchair. All you need is a computer which is linked to the Internet. Shopping on the Internet is becoming increasingly popular. In the United States, people spent over US $2.5 billion on Internet shopping in 1998. This figure is expected to reach US $11 billion by the year 2004.
People can shop for a variety of products on the Internet. Physical products include items such as books, CDs, clothes and food. These types of products are the most common purchases through the Internet. You can also buy information products such as on-line news or magazine stories, or you can download computer software through the Internet. Services such as booking airline tickets, reserving hotels or renting cars are also available on the Internet. You can also go shopping on the Internet for entertainment services and take part in on-line games.
Internet shopping offers a number of benefits for the shopper. The most important advantage is convenience. You can shop when you like as the on-line shops are open 24 hours a day and you don’t have to queue with other shoppers at the checkout counters. Secondly, it is easy to find what you are looking for on the Internet. Even out-of-print books may be ordered on line. Finally, it is often cheaper to buy goods through the Internet, and you can tell the shop exactly what you want.
The main disadvantage of Internet shopping is that you cannot actually see the products you are buying or check their quality. Also, many people enjoy shopping in the city and miss the opportunity to talk to friends. Some people are worried about paying for goods using credit cards, so Internet companies are now finding ways to make on-line payment safe.
Internet shopping is sure to become more and more popular in the years ahead. It promises to change the way we buy all kinds of things—from tonight’s dinner to a new car.

In the passage, which of the following disadvantages of Internet shopping is not mentioned

A. customers cannot actually see the products they are buying
B. customers cannot check the product’s quantity they are buying
C. many people enjoy shopping in the city and miss the opportunity to talk to friends
D. some people are worried about paying for goods using credit cards

下列关于货物运输合同的说法中，正确的是( )。

A．货物运输合同的标的是货物

B．货物运输合同是为第三人利益而订立的合同

C．货物运输合同的当事人是托运人、承运人、收货人

D．货物运输合同的当事人是托运人、承运人