下列操作中，能改变物体发出声音的音调的是（　　）

A．用力拨动琴弦

B．给二胡的弦上涂一些松香

C．用力敲打鼓

D．转动小提琴的旋钮调节弦的松紧程度

句型转换。

1. He has a tennis racket. (改否定句) 

    He _______  _______ a tennis racket.

2. That is her watch. (改为复数形式) 

                  are her              . 

3. I have a soccer ball. (一般疑问句)

    _______  _______ have a soccer ball？

4. Is the soccer ball under the bed? (作否定回答) 

    _______, it _______.

5. That is a backpack. (对划线部分提问)

    _______  _______ in English?