一个梯形高是5dm，如果上底增加2dm，下底不变，面积增加[ ] A．10dm2

阅读理解。

     Hello! I am Julia. My mom and I are from the U.S.A. . I am thirteen now. I'm in Class 6, Grade 7. Lingling is my friend.

She is from Yunnan. Her QQ number is 52656523. We are in the same school. She is in Grade 7, too. But she is in Class

7. She is fourteen. My mom is Nancy. She is a teacher in my school. She has a nice car.   

1. How old is Julia?

A. 13       

B. 14         

C. 15

2. Lingling's QQ number is        ?

A. 52656523    

B. 52655633  

C. 52655623

3. Lingling is in        ?

A. Class 6, Grade 7.      

B.Class 7,Grade 7.  

C.Class 7, Grade 6.

4. Where is Nancy from?

A. China            

B. England            

C. the U.S.A.

5. Which is RIGHT(哪一项是正确的)?

A. Lingling is from the U.S.A.        

B. Nancy has two cars.  

C. Julia, Lingling and Nancy are in the same school.

会计从业资格证书实行注册登记制度。 ( )

下列物质中，既有离子键又有共价键的是（   ）

A．Ca(NO₃)₂

B． KOH

C． H₂O

D． NH₄F

目前主要应用于银行、税务、商店等票据打印的打印机是( )。

A．针式打印机

B．点阵式打印机

C．喷墨打印机

D．激光打印机

突出矿井的通风系统应当符合哪些要求？