active immunizing agent的用法和样例：
- In 1975, the Food and Drug Administration (FDA) concluded that diphtheria toxoid “is not as effective an immunizing agent as might be anticipated.
- The rats in pure injury group did not perform active immunity.
- Influenza may be prevented by active immunization with a polyvalent killed or subunit vaccine.
- Active immunization with NP30 could induce a good protection in goats against the infection with Schsitosoma cercariae.