铅引起机体的主要早期变化之一是（） A.小血管痉挛 B.卟啉代谢障碍 C.对神经鞘细

Tuesday is the _____ day of the week.  [ ]

A. first    

B. second    

C. third

某窗间墙截面1500mm×370mm，采用MU10烧结多孔砖，M5混和砂浆砌筑，其孔洞全部灌实。墙上钢筋混凝土梁截面尺寸b×h=300mm×600mm，如图所示。梁端支承压力设计值N_l=60kN，由上层楼层传来的荷载轴向力设计值N_u=90kN。砌体施工质量控制等级为B级，结构安全等级为二级。

试问砌体局部抗压强度提高系数γ，与下列何项数值最为接近（）

A．1.2

B．1.5

C．1.8

D．2.0

To extinguish (熄灭) different kinds of fires, several types of fire extinguishers have been invented. They must be ready for immediate use when fire breaks out. Most portable (手提式的) kinds operate for less than a minute, so they are useful only on small fires. The law requires ships, trains, buses and planes to carry extinguishers.

Since fuel, oxygen (氧气) and heat must be present in order for fire to exist, one or more of these things must be removed or reduced to extinguish a fire. If the heat is reduced by cooling the material below a certain temperature, the fire goes out. The cooling method is the most common way to put out a fire. Water is the best cooling material because it is low in cost and easy to get.

Another method of extinguishing fire is by cutting off the oxygen. This is usually done by covering the fire with sand, steam or some other things. A blanket may be used do cover a small fire.

A third method is called separation, which includes removing the fuel, or material easy to burn, from a fire, so that it can find no fuel.

The method that is used to put out a fire depends upon the type of fire. Fires have been grouped in three classes. Fires in wood, paper, cloth and the like are called Class A fires. These materials usually help keep the fire on. Such fires can be stopped most readily by cooling with water.

68. If a fire breaks out on a bus, which of the follow should be ready there for you to use?

A. Sand           B. Water         C. A blanket.           D. An extinguisher.

69. To cover a small piece of burning wood with a basin in order to stop the fire is an example of         .

A. separating the fire                                 B. reducing the heat

C. removing the fuel                                 D. cutting off the oxygen

70. In choosing how to put out a fire, we should first be clear about          .

A. when it breaks out                                B. how it comes about

C. what kind it is                                       D. where it takes place

71. What would the author probably discuss in the paragraph that follows?

A. Another class of fires                                   B. Another type of extinguishers

C. How fires break out.                                D. How fires can be prevented.

任何时候会计科目都可以删除和更改其属性的。（）

教育心理学的具体研究范畴是围绕______相互作用过程展开的。