简述载波侦听多点接入/冲突检测的工作过程？

Because earthquakes happen without warning, it’s important to take measures now to prepare. Because you don’t know where you will be when an earthquake happens, prepare some supplies for your home, workplace, and car.

　　1. Water

　　A person needs at least 1/2 gallon(加仑) of water daily just for drinking. Store at least 1 gallon of water per person per day and be prepared for a 72-hour period. It is suggested that you buy bottled water. Keep bottled water in its original container and do not open it until you need to use it. Also, do check the “use by” date.

　　2. Food

　　It’s always a practical idea to keep a supply of non-perishable(不易腐烂的) food on hand. Have an enough supply of canned food, powdered milk, dried fruits, non-salted nuts and canned juices for at least 72 hours.

　　3. Torch(手电筒) and spare batteries (电池)

　　Keep a torch beside your bed, at your place of work, and in your car. Do not use matches or candles after an earthquake until you are sure that no gas leaks(泄露).Prepare a battery-powered radio and spare batteries. Most telephones will be out of order, so radios will be your best source of information.

　　4. Clothes

　　If you live in a cold place, you must think about warmth. You might not have heat after an earthquake. Think about your clothing and bedding supplies.

小题1:Why should people prepare themselves for an earthquake?

A．Because earthquakes can be known before they happen.

B．Because earthquakes take place without warning.

C．Because earthquakes usually take place in the neighborhood.

D．Because it’s people’s daily work to prepare the earthquakes.小题2:You should prepare all of the following except ______.

A．powdered milk

B．fresh vegetables

C．dried fruits

D．canned juices小题3:According to the article we know that ______.

A．we need to prepare some supplies only at home

B．a telephone is the most important prepared thing

C．after earthquakes you’d better use torch first but not matches

D．clothes are used to protect your head小题4:If you live in a cold place, you should prepare _______.

A．some warm clothes and bedding supplies

B．some hot water

C．some batteries

D．some torches

隔姜灸的适应病证是（）

A.瘰疬、初起的肿疡

B.哮喘、肺痨、瘰疬

C.吐泻并作、中风脱证

D.因寒而致的呕吐、腹痛

E.命门火衰而致的阳痿、早泄

建筑施工中，在高处实施电焊、气割作业时，对作业的周围和下方缺少防护遮挡，属于引发火灾和爆炸事故的( )。

A．基础原因
B．直接原因
C．间接原因
D．根本原因

下列对于中成药的论述错误的是（）

A.以中医药理论为指导进行研制

B.按照规定的处方与制法生产

C.标明规格、功能主治、用法用量

D.均属于非处方药

E.有特有的名称

男性，55岁，因急性心肌梗死收治入院，突然出现心尖部收缩期杂音，无震颤，心衰症状明显加重，最可能的原因是（）

A.左心室扩大引起二尖瓣关闭不全

B.心率增快

C.合并感染性心内膜炎

D.室间隔穿孔

E. * * 肌功能失调或断裂