根据提示完成句子，每空一词

1. A: What's that in English?

    B: It's a _____ (书). 

2. A: What's this on the desk?

    B: It's a _____ (录音磁带).

3. A: Where's your _____ (包)?

    B: It's on the bed.

4. Who's that _____ (女孩)?

鸡兔共有40个头，鸡的腿比兔的腿多50条，鸡有（    ）只，比兔多（    ）只。