2015年職稱英語衛(wèi)生類語法否定句：
他的設計肯定還沒完成。
誤：He mustn't have completed his design.
正：He can't have completed his design.
對比較有把握的推測，肯定句中用must，而否定句中用can't，對過去的推測，在must和can't后接完成形式。
2015年職稱外語等級考試報名指南
