我发现历史课上很难保持清醒。

I find it so difficult to stay ___awake during history lessons.

我喝很多咖啡来保持清醒。

I drink a lot of coffee to keep me ___awake.

她感到非常紧张，以至于晚上睡不着。

She felt so nervous that it kept her ___awake at night.