that were supposed to prevent anything like it happening again.以期防止这样的悲剧再次发生

supposed to猜想会； 应该

I'm supposed to be there at five.

我得五点钟到那儿。

You're supposed to pay the bill by Friday.

你最晚在星期五结清这笔帐。

Vioxx, used to treat rheumatoid arthritis and menstrual pain,万络曾用来治疗类风湿性关节炎和痛经

used to过去常常

I weigh less than I used to.

我的体重比以前轻了。

Jack used to assist Mary in her lessons.

杰克过去常常帮助玛丽学习功课。