【答案解析】abide by：坚持；遵循。stick to：坚持；遵循。He must stick to the contract．他必须遵守合同。Persist in：坚持。Why do you persist in writing such things?你为什么老是写这些东西?safeguard：保护。Vaccination safeguards us from smallpox．接种疫苗可防天花。apply：应用；申请。I have applied for a passport．我已申请办理护照。