练习材料：
The Greenwood Boys are a group of pop singers. At present, they are visiting all parts of the country. They will be arriving here tomorrow. They will be coming by train and most of the young
people in the town will be meeting them at the station. Tomorrow evening they will be singing at the Workers' Club. The Greenwood Boys will be staying for five days. During this time, they will give five performances. As usual, the police will have a difficult time. They will be trying to keep order. It is always the same on these occasions.
任务配置：L0+L4
知识笔记：wood /wʊd/ 这里的/ʊ/是松元音，短促，/u/紧元音，声音长，=/u：/
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练习感悟：坚持不易，尤其我这种间歇性踌躇满志的，永远对自己狠不下心。。。坚持一天算一天吧，哎。今天琢磨半个小时，终于搞懂了这个/u/和/ʊ/，其实就是前者读音长，后者读音短促，音标就是学了忘，忘了学。。。
