【正确答案】 A

【答案解析】[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. 接种疫苗可预防天花。apply：应用；申请。I have applied for a passport. 我已申请办理护照。