读短文，用“√”或“×”判断正误。

      This is my bedroom. There is a bed, a shelf, a table and a chair. I have many toys. This is my doll. It's on

the bed. There are many story-books on the shelf. There are five books on the floor. Five pencils are under the

chair. What an untidy room!

( ) 1. This is my living room.

( ) 2. I have many toys and story-books.

( ) 3. The doll is on the chair.

( ) 4. What a beautiful room!

( ) 5. Five pencils are under the bed.

( ) 6. All books are on the shelf.

( ) 7. This is an untidy room.

对10名25岁以上的山区健康男子测量脉搏次数(次／分)，用t检验与全国正常男子资料进行比较，按a=0.05的检验水准，自由度为（ ）。

A．V=9

B．V=19

C．V=8

D．V=20

E．V=18