重点讲解：
1. engage in
参与；从事；
eg. Faculty who engage in research seem to have more knowledge to pass on to their students.
从事研究工作的教师似乎有更多的学识可以传授给学生。
eg. So we have to be very cautious of you know what kind of activities we engage in.
所以我们对参加哪种集体活动都会谨慎的考虑。
2. be dedicated to sth./doing sth.
奉献给；献身于；致力于；
eg. He was a consultant physician, a serious man dedicated to his calling.
他是个会诊医生，严肃认真，对自己的职业全身心投入。
eg. Health products company dedicated to innovative research and development.
公司致力于健康产品的创新研发。
3. in vain
徒劳；白费力气；
eg. It became obvious that all her complaints were in vain.
很明显她所有的抱怨都是白费口舌。
eg. The thief tried in vain to open the locked door.
小偷试图把锁着的门打开，但枉费心机。