The authorities often know that sex offenders will attack again when they are released.

当局一般都知道性犯罪者在获释后往往会再次犯案。

The contraceptive pill is the worst offender, but it is not the only drug to deplete the body's vitamin levels.

避孕药的危害最大，但是它并不是唯一一种消耗体内维生素的药物。