Which tense should properly complete this sentence? 'The company ______ its data protection protocols since the cybersecurity incident last year.'
答案解析
Core concept: Present perfect continuous tense. The temporal phrase 'since...' requires a continuous action from past to present. 'Have guarded' (A) correctly uses present perfect tense. Simple past (B) indicates completed action, present simple (C) describes habits, and present continuous (D) lacks temporal scope.
正确答案：A