（）又称为流通中心，它除对货物进行保管外，更多的是进行流通加工、装配、包装、理货及配

【说明】 下面是一个Applet程序，其功能是将完整的图像显示于Applet的区块中，然后可以通过拖动鼠标让图像随着鼠标拖动的轨迹而移动。 程序运行结果如图5所示。

import java. applet. *； import java. awt. *； /* ＜applet code="ex4_7.class"，width=800 height=400＞ ＜/applet＞ */ public class ex4_7 extends Applet{ private |mage ilmg； private int xPos，yPos； public void init(){ xPos = yPos= (1) ； ilmg=getlmage( (2) "ex4_7.jpg")； } publicvoid paint(Graphics g){ g. drawlmage(ilmg，xPos，yPos， (3) )； } public boolean (4) (Evente，int x，int y){ xPos=x； yPos=y； (5) ； return true； } } ex4_7. html ＜HTML＞ ＜HEAD＞ ＜TITLE＞ ex4_7 ＜/TITLE＞ ＜/HEAD＞ ＜BODY＞ ＜appletcode=" ex4_7. class" width =800 height =400 ＞ ＜/applet＞ ＜/BODY＞ ＜/HTML＞

A person steps on what seems like solid ground but discovers with horror that the ground is giving way underfoot. The person struggles desperately but is trapped. There is no escape. Slowly the person sinks deeper and at last is gone. The solid ground was solid only in appearance. It was actually quicksand, which is a deep mass of fine sand mixed with water.

How is quicksand formed? Water pushes up from below the surface and is held by the sand. The grains of sand are forced apart by the water. They cannot hold any weight. The subsurface water may have come from a spring, a river, or a stream. Sometimes pools of water near beaches become filled with sand. When the soil under these pools does not allow for good drainage(排水), the sand can become stretches of quicksand.

Is it true that a person who steps into quicksand is doomed to die? No, for people have fought their way from quicksand to firm land again. It is panic(恐慌) that creates the condition that can result in death, for the more a person struggles, the worse matters become. Quick movements will make the sand yield for a time, but then it rushes back and settles solidly around the body.

People trapped in quicksand should either lie back with arms outstretched, or not move at all. When the weight of the sand around his body has displaced equals that person’s weight, the victim will stop sinking. With feet held still, and with slow movements of the arms, as in the backstroke(仰泳) in swimming, people have managed to roll to safety and reach firm ground.

小题1:Quick movements by a person trapped in quicksand will _______.

A．help the person reach firm ground

B．help prevent panic

C．make the same sand yield temporarily

D．make the sand hold the person’s weight小题2:Quicksand is _______.

A．a mass of fine sand mixed with water

B．formed only along rivers

C．found below subsurface water

D．solid ground小题3:Which statement does the article lead you to believe?

A．Stretches of quicksand are found only under the sea.

B．People should never try to escape from quicksand.

C．It is hard to keep calm if you fall into quicksand.

D．Only heavy people can be trapped in quicksand.小题4:The passage mainly tells about _______.

A．what solid ground looks like

B．the nature of quicksand

C．stepping into quicksand

D．escaping from quicksand

进程是程序的一次执行过程，是操作系统进行资源调度和分配的一个独立单位，其基本特征是( )。

A．并发性、实时性、交互性

B．共享性、动态性、成批性

C．并发性、异步性、分时性

D．动态性、并发性、异步性

选择育种的基本原理是作物品种的（）和（）。

下列哪种药物是降压药（）

A.倍他乐克

B.卡托普利

C.氢氯噻嗪

D.心痛定

E.消心痛