重点讲解：
1. used to do sth. 过去常常；过去曾；
例句：The place used to be a stretch of barren land.
早先这里是一片不毛之地aL_)QuG2sI.qz;U9bYN。
2. be involved in 卷入的；参与的；与…有密切关联的；
例句：He was involved in a lawsuit because of his heedless remarks.
他因冒失的言论而卷入一场官司IikEQHtn4d0。
3. be interested in 感兴趣的；有兴趣的；关心的；
例句：He is very interested in what are called popular songs.
他对所谓的流行歌曲很感兴趣80,#1a|9#Lc~CJ。