我在讲座期间逐渐睡着了。

I ___drifted ___off during the lecture.

她不情愿地逐渐入睡，思绪飘向了米兰的回忆。

She ___drifted ___off unwillingly, her mind wandering to memories of Milano.

洗了个热水澡后，他在几分钟内就逐渐入睡了。

After taking a warm bath, he ___drifts ___off to sleep within minutes.