何谓动力燃烧？何谓扩散燃烧？何谓过渡燃烧？

阅读理解。    

 Here are some American classroom customs :      

     If the teacher asks a question, you are expected to give an answer. If you do not understand the

question, you should put up your hand and ask the teacher to repeat the question. If' you do not know the answer, it is all right to tell the teacher that you do not know. Then he or she knows what you need to

learn.      

     There is no excuse for not doing your homework.  If you are absent (缺席的) ,  you should call your

teacher or someone who is in your class and ask about the assignment(作业).  It is your responsibility(责任)  to find out what the assignments you have missed are. It is not the teacher's responsibility to remind

you of the missed assignments.      

     You must not be absent on a test day. If you are seriously ill, call and let the teacher know you will not be there for the test. If your teacher allows make-up tests, you should take the test within one or two days after returning to class. Serious illness is the only reason for missing a test.      

     Be on time !  It is considered( 认为)  rude to be late. Also, it disturbs other students. If you must come in late, be sure to do it quietly. Have your books and papers out of your bag before you come into the

room. Then go to your seat and sit quietly. In the US it is not necessary to knock before you enter the

classroom. If you must leave during class ,  do so quietly.  There is no need to ask the teacher's

permission. Entering a teacher's office or any office with a closed door without knocking first is not

acceptable.  Knock first , then wait to be invited in.        

     Wearing a hat in class is considered impolite by many teachers. Some teachers may ignore it, but you

should ask permission first.  

根据短文内容，回答下列问题。

1. What should a student do if he or she doesn't understand the teacher's question?  

__________________________________________

2. If a student misses a class, how can he or she find out the assignment?    

__________________________________________

3. What is the only reason for missing a test?

__________________________________________

4. Is it necessary for a student to knock before he or she enters the classroom?  

__________________________________________

5. Put the sentence "Wearing a hat in class is considered impolite by many teachers. " into Chinese.

__________________________________________

某单位业务人员张某在一家酒店招待业务单位人员，发生招待费8000元。事后，他将酒店开出的发票金额改为18000元，并作为报销凭证进行了报销。张某的行为属于（）。

A.伪造会计凭证行为

B.变造会计凭证行为

C.做假账行为

D.违反招待费报销制度行为

“公司实施税务管理要求所能增加的收益超过税务管理成本”体现的原则的是(　)。

A．税务风险最小化原则

B．依法纳税原则

C．税务支出最小化原则

D．成本效益原则

两重物A和B，其质量为m₁和m₂，各系在两条绳子上，此两绳又分别围绕在半径为r₁和r₂的鼓轮上，如图所示。设m₁r₁＞m2r，鼓轮和绳子的质量及轴的摩擦均略去不计。则鼓轮的角加速度为（）。

A.A

B.B

C.C

D.D

什么是塔式建造法？