[说明] 成都外国语学院将于2009年12月15日召开每年一度的全国英语学术研讨会。今年的主题是语言学在当代的发展。外国语学院拟邀请伦敦大学学院著名语言学专家Professor Wells来华参加研讨会，并做报告。请以成都外国语学院的名义写一封邀请信。
Words for reference：学术研讨会：symposium语言学：linguistics
伦敦大学学院：University College of London

A water bed can be a lot of fun. It is a very big bag that’s filled with water. The water can be made nice and warm. You move up and down as the water moves. It’s something like being on a boat. It rocks you to sleep.A cot is a very light bed. When it’s not being used, you can fold it up and put it out of the way. Then you can take it out again when you need it. You can use it for a friend. A cot is just right for someone who is sleeping over,In some places people sleep on mats. The mats are made of long pieces of grass. People take them out at night on the floor. In the morning people take them up off the floor and roll them up. Think of how much room a house has with no beds!