用括号内所给单词的适当形式填空。

1. —Where _____ (be) the backpacks?

    —They are on the sofa.

2. Look! Your _____ (tape) are on the bed.

3. There are some _____ (chair) in the room.

4. Please take these _____ (thing) to your brother.

5. Can you _____ (bring) your new (新的) photos here this afternoon?

根管充填的目的是

A．严密封闭主根管及侧枝根管，防止再感染
B．提高牙齿防御能力
C．防业根折
D．防止牙齿变色
E．使根尖病变愈合