重点讲解：
1. extraterrestrial life 外星生物
例句：Of course, there is always the chance that extraterrestrial life will find us first.
当然，很有可能外星生命先发现我们。

2.tear up 撕毁
例句：I suggest that you tear up the letter and start over again.
我建议你把这封信撕了，再重头开始写。

3.turn it upside down 把它颠倒；完全颠覆
例句：It was stupid of you to turn it upside down without closing the lid.
你没有盖上盖子就把它倒过来，真是糊胡涂。

4.protect..against 保护；帮助抵抗
例句：Container scanning services are offered to help protect against security risks associated with international trade .
集装箱扫描服务将帮助防止与国际贸易有关的安全风险。