D
An Englishman named Phil Shaw invented extreme ironing in 1997 because he was bored doing ironing at home.
Extreme ironing is a special kind of outdoor sport. It combines (使结合)danger and excitement with practical ironing.
Who does extreme ironing People all over the world who like danger do it. There are about 1000 people around the world who do extreme ironing. There are extreme ironing clubs and groups in Britain, Germany, South Africa, New Zealand and the United States. You don’t have to have any special qualifications(资格证明)to do it. In fact, anyone can do it. However, it is better to start ironing in your back yard(院子) before you start to iron on top of a mountain.
There are, of course, some rules in extreme ironing. The ironing must be outdoors. You must take an iron, an ironing board, and something that you actually iron to get the wrinkles out. Outdoors includes faraway and unusual places, such as on top of a mountain, while skiing, snowboarding, skydiving, or under water. There are no limits. The more unusual the better. However, you should plan carefully because weather conditions can suddenly change on mountains, for example. You should not do extreme ironing on your own.
What kind of things should you have Your must have a real iron. Travel irons are acceptable. You must not use plastic or toy irons. The clothes you iron must he at least the size of a hand towel. It shouldn’t be just a handkerchief. The board doesn’t have to be a full-size board, but that is preferred. It must be one meter long and thirty centimeters wide and have legs. You must also have proof (证据) of ironing that is either a photo or a video, and it should show a recognizable landmark. Be aware (意识) that people have already ironed near the top of Everest, the highest mountain in the world, and in the Blue Hole in Egypt, one of the most dangerous places to dive. However, there are still many records to break. Iron on!
Which is the best advice for beginners to do extreme ironing ( )
A．Doing extreme ironing alone.
B．Beginning ironing in their back yards.
C．Starting ironing on top of a mountain.
D．Joining extreme ironing clubs or groups first.
（g）+O
2SO
（g），已知反应进行到10秒时，SO