1. Some bottles dropped onto the floor.解析：根据下文的so many bottles.可知。

　　2. Why do you collect bottles? 解析：根据下文的答语Because I want to make toys out of them.可知。

　　3. That's an interesting idea. 解析：根据句意老师赞同他做法"那是个好主意"。

　　4. Have you already made some toys? 解析：根据下文的答语Yes, quite a few.可知。

　　5. Can you show some to us one day? 解析：根据下文的答语Of course, I'll bring a few here tomorrow.可知。