2017年職稱英語衛(wèi)生類a否定句考點(diǎn)（9）

他的設(shè)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。