重点讲解：
1. on sale
出售；上市；
eg. The new commemorative stamps will be put on sale next week.
新的纪念邮票将于下星期发售。
eg. Tickets are on sale from the booking office.
售票处正在售票。
2. under threat
受到威胁；
eg. She lives daily under threat of violence.
她每天都生活在暴力威胁之下。
eg. Even the most security-conscious computer user is under constant threat from computer viruses.
即使是有强烈安全意识的计算机用户也时刻处于计算机病毒入侵的威胁下。
3. carry out
实施；执行；实行；
eg. The police will carry out a dawn raid.
警方将在拂晓展开突然搜查。
eg. He balked me to carry out my plan.
他阻止我实施我的计划。
