﹣5的绝对值是

    Mr. Jackson was tired of living in his old house in the countryside and wanted to sell it and buy a better one. He tried to sell it for a long time, but was not successful, so at last he decided to go to an estate agent（房产经纪人）.

    The agent advertised the house straight away, and a few days later, the owner saw a very beautiful photograph of his house, with a wonderful description of his garden in an expensive magazine.

    Having read the advertisement through, the house owner hurried to phone the estate agent, saying, “I'm sorry, Mr. Jones, but I've decided not to sell my house after all.” “Why?” the agent asked in a surprised voice. “Because from the advertisement in that magazine I can see it's just the kind of house I've wanted to live in all my life.”

如图所示，一束光在空气和玻璃两种介质的界面上同时发生反射和折射（图中入射光线、反射光线和折射光线的方向均未标出），其中折射光线是____ （用字母表示），反射角等于____ ．折射角____ ．