Which tense is correct for the blank: Since 2020, the global economy ______ significant changes.
答案解析
**Core Topic**: Grammar (present perfect tense). **Key Clue**: 'Since 2020' requires a continuous action. **Analysis**: C. 'has undergone' fits the present perfect structure. A/B use simple tenses, ignoring 'since'. D. focuses on ongoing action, not duration. **Common Mistake**: Misusing simple past (B) without recognizing 'since'.
正确答案：C