We should require that every student is immunized against hepatitis B.

我们应该要求每一位学生都注射乙肝疫苗。

The monkeys used in those experiments had previously been immunized with a vaccine made from killed infected cells.

这些实验中所用的猴子事先都已接种了由被杀死的感染细胞制成的疫苗。

All parents should have their children immunized.

所有的父母都应该让孩子接种疫苗。