重点讲解：
1. step up 增加(数量等);提高(速度、强度等)；
Fears of a possible faltering of the recovery forced the government to step up stimulus spending.
对经济复苏可能步履维艰的恐惧，迫使政府加大了刺激性支出的力度。
2. preside over 负责；主持；
Who preside over the meeting have not be decided.
这个会议要谁来主持还未决定。
3. bring forward 提出（观点）；提交（议案）；
In order to settle increasing air traffic, ICO bring forward the concept of free flight.
为了解决日益增长的空中交通量，国际民航组织提出了自由飞行的概念。
4. run afoul of （与法律、规章等）相抵触，有冲突；
His business methods were not entirely honest, and he soon ran afoul of the law.
他做生意的方法不很老实，不久就犯了法。