重点讲解：
1. step up 增加(数量等)；提高(速度、强度等)；
He urged donors to step up their efforts to send aid to Somalia.
他敦促各捐赠方加快速度将援助物资送往索马里s6efzf@*0DJe0。
2. hit back at 反击；还击；
The President has hit back at those who have criticised his economic reforms.
总统对那些批评过其经济改革措施的人进行了反击x[%prusWRVfgBaTo。
3. stand aside (从重要职位上)退下，下台(常为了让位给别人)；
The President said he was willing to stand aside if that would stop the killing.
总统说，如果他下台能让杀戮停止的话，他愿意这样做2tNh@@.P_Cf7M%。
4. stand down (从重要职位上)退下，下台(常为了让位给别人)；
Profits plunged and he stood down as chairman last January.
因利润骤降，他作为董事长于去年1月辞职了DP%%.dGR)V*q&HO。