重点讲解：
1. head to
前往；引至，通到；
eg. Disobeying the law can head to trouble.
不守法可能会引起麻烦。
eg. In the summer many residents head to cape cod and newport beach, rhode island.
一到夏天，许多居民就前往科德角、纽波特海滩和罗德岛。
2. be vulnerable to
易受伤害的；易受影响的；
eg. But in today's economy, educated, white-collar workers also are vulnerable to downsizing.
但是,在今天的经济中，受过教育的白领工人也同样容易受到裁员的攻击。
eg. A system without anti - virus software will be vulnerable to a hacker attack.
没有防毒软件的系统很容易被黑客攻击。
3. in dange of
处于…危险之中；
eg. The plant is now in danger of extinction.
这种植物现在有绝种的危险。
eg. He was in danger of losing his life.
他有失去生命的危险。