A .One day, Mr. Li and Mr.King go to London to see their friend Tom. They don't know much English and they don't know about London, either.

B .They go up to him and ask the way. The man smiles but says nothing. Then he puts his hand into his pocket (口袋）and takes out a book. He opens the book and reads, “I'm sorry, I can't speak English.”

C .Mr. Li and Mr King have a good friend His name is Tom Smith. He lives in London.

D .In the evening, they find their friend's home with the help of a policeman (警察).

E .And they can't find Tom's home. They walk in the street for a long time. Then they see a man near a bus stop.

在一个不透明的布袋中装有红色、白色玻璃球共60个，除颜色外其他完全相同．小明通过多次摸球试验后发现，其中摸到红色球的频率稳定在25%左右，则口袋中红色球可能有（　　）

一天，某地凌晨5点的气温是零下4℃，可以记作____℃。

若$\sqrt{x-1}+\sqrt{x+y}=0$，则xy的值为（   ）