Directions: Complete the following passage by using ONE word that fits the context．

Visit the Edinburgh Festival

Every year, thousands of people come to Edinburgh, the capital city of Scotland, to be part of the Edinburgh Festival．For three weeks every August and September the city is filled with actors and artists from 小题1: over the world．They come to Edinburgh  小题2: the biggest arts festival in Britain．During this time the streets of the city are alive with music and dance from  小题3:  morning till late at night．You can even see artists painting pictures on the streets．One of the best parts of the Festival is the "Fringe", 小题4:  students do comedy shows in small halls and cafés．

小题5:   of thousands of tourists come to the Festival to see new films and plays and hear music performed by famous musicians．This year, you can see over five hundred performances  小题6:   actors from more than forty countries．

The tickets for these performances are quite cheap and it is usually easier to see your favorite stars in Edinburgh 小题7:  it is in London．Come to Edinburgh next summer, but remember it can be difficult to find a room, 小题8: why not book your hotel now?

（4分）鸡蛋腐败变质时会产生一种无色、有臭鸡蛋气味的硫化氢气体（H₂S）。硫化氢气体是一种大气污染物，它在空气中点燃完全燃烧时，生成二氧化硫和水。请回答：

（1）上述信息中，属于硫化氢气体物理性质的是_______________________。

（2）已知硫化氢气体能溶于水，密度比空气大，则可用               法收集硫化氢。

（3）写出硫化氢在空气中完全燃烧的文字表达式： ____________        __     _。