重点讲解：
1. be grateful for 感激的；表示感谢的；
We should be grateful for your help.
对您的帮助我会非常感激。
2. impose on 强制实行；强加；
The government has imposed export restraints on some products.
政府对一些产品实行了出口控制。
3. withdraw from 退出(活动或组织)；
In response, banks withdraw from marginal markets, reducing competition.
针对这种形势，银行纷纷撤出次要市场，以降低竞争强度。
4. come into effect 实施；生效；
This law has not come into effect yet.
这部法律尚未生效。