1.go missing 失踪；不见；丢失

He is one of hundreds, perhaps thousands of children who go missing in China each year, victims of roving criminal gangs preying on vulnerable areas.
每年像小锐聪一样失踪的孩子还有成百上千个，一些地区的人口贩卖活动非常猖獗。

Examples abound of databases being stolen: disks full of social-security data go missing, laptops loaded with tax records are left in taxis, credit-card numbers are stolen from online retailers.
例如，大量数据库被盗；装满社会保险数据的光盘不见了。 载有税务记录的笔记本电脑被遗忘在出租车上，信用卡号在线使用时被盗。

2.have to 必须；不得不；只好

You have to consider what to do next.
你必须考虑下一步该做什么。

You have to keep after your son if he refuses to be housebroken.
如果你儿子不服管教的话，你必须整天跟在他的身边。