重点讲解：
1. focus on 集中（注意力）；关注；
例句：Throughout the exercise, focus on keeping your abs tight.
整个锻炼过程中，注意要紧绷腹肌KauMEC_Hex~q%h]5T。
2. participate in 参与；参加；
例句：They expected him to participate in the ceremony.
他们希望他参加典礼a7]dlNoR,r6rr8O.wVqb。
3. complain about 抱怨；发牢骚；
例句：The neighbours always complain about the noise.
邻居们总是抱怨噪音问题rCk8qdj_RH_nB。
4. learn from 向……学习；
例句：There is a great deal to learn from Hal's expert approach.
从哈尔熟练的方法中可以学到很多EfuwcfcM6NOBK.4UMjg。
5. no doubt 无疑地；必定；
例句：She's a very sweet woman, as you no doubt know by now.
她是一个非常温柔的女人，你现在肯定知道了)NklF&GD^-C^。