1.go missing 失蹤；不見；丟失

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.
每年像小銳聰一樣失蹤的孩子還有成百上千個，一些地區的人口販賣活動非常猖獗。

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，大量數據庫被盜；裝滿社會保險數據的光盤不見了。 載有稅務記錄的筆記本電腦被遺忘在出租車上，信用卡號在線使用時被盜。

2.have to 必須；不得不；只好

You have to consider what to do next.
你必須考慮下一步該做什么。

You have to keep after your son if he refuses to be housebroken.
如果你兒子不服管教的話，你必須整天跟在他的身邊。