Here are the best options for each sentence:

1. Emma has a habit of going **over** her notes before an exam.
2. Ms. Davis usually tells us to note **down** important grammar rules.
3. Marie often turns **on** subtitles when she watches English movies.
4. It's common to come **across** unfamiliar words when you read English books.
5. "Be sure to look **up** for words to understand their meanings," the teacher said.