下列属于历史结构的（） A.经济结构 B.政治结构 C.理结构 D.文化结构

一般泡沫灭火器的灭火原理是( )。

A．减少明火

B．隔绝氧气

C．增加湿度

D．制造泡沫

【选修3-4选做题】

在折射率为n、厚度为d的玻璃平板上方的空气中有一点光源S，从S发出的光线SA以入射角θ入射到玻璃板上表面，经过玻璃板后从下表面射出，如图所示。若沿此光线传播的光从光源到玻璃板上表面的传播时间与在玻璃板中的传播时间相等，点光源S到玻璃板上表面的垂直距离l应是多少？

一患者右耳前刀砍伤缝合后，局部肿大，穿刺有清亮液体，最可能的原因是（）。

A.组织活动出血

B.淋巴管损伤

C.腮腺腺体或导管损伤

D.脑脊液漏

E.与口腔相通

In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

In recent years, there has been a dramatic increase in the range of media used to (71) information. Initially, communication was limited to simple forms of (72) such as voice and paper. This century, however, has witnessed the introduction of a greater variety of media types such as the telephone and visual forms of media. In the latter part of the century, this trend has accelerated and there is now a wide range of media types available to convey information. These advances provide a great opportunity for new developments in a range of areas such as education and commerce. However, there are also a number of problems associated with the growth of (73) in society. In particular, there is a great danger of creating information (74) . This problem can be seen, for example, in business where executives are required to make decisions based on an ever increasing variety and volume of information. (75) problems are also occurring in areas such as government, health care and education.

（71）是（）

A.speak

B.convey

C.tell

D.spread

试述春温章中白虎汤的变化应用？