单项选择题 绿色建筑的基本要求可概括为四节一环保，其中四节包含以下:

单项选择题 Please compare Letter A with Letter B, and comment on both of them. Then, revise your favorite one for effectiveness. You might rewrite or add any information if necessary. Letter A Dear Sir We are writing to ask if you would like to buy some of our new bears. They are really good and we have sold many. Tom Teddy Bear is 30 cm high and dark brown. He has an appealing face, and he talks, crawls and clings to people-with a little help from his batteries. Why not try 20 or 30 teddies to start with? You can have some more later if you like them. Call me and we will sort something out. Yours faithfully Letter B Dear Mr Hope Tom Teddy Bear We are writing to tell you about our brand-new product which, we think, will revolutionize the teddy bear world. Tom Teddy Bears stands a full 30 cm high and is made of dark brown plush fur. He talks, crawls and even clings to people. He operates via 4 AA size rechargeable batteries. Tom Teddy Bear will normally be $9.99 trade each, but for a limited period only we are offering you supplies at $7.50. Why not try 20 or even 30 at this very special price? We know you will be pleased to hear that one of our representatives will call on you within the next few days to show you Tom Teddy Bear in person. We are sure that you will be as impressed as we are with this exciting new product. Yours sincerely Sara Wang

单项选择题 下列通讯工具在我国近现代出现的先后顺序是（）