O Salutaris Hostia - O Saving Victim - is usually sung at the beginning of Exposition.
Here are some flash card sets if you would like to use Quizlet to learn the vocabulary:
Then there is usually a time for Adoration, when we can sing a few more reverent hymns.
Tantum Ergo - Down in Adoration Falling - is usually sung at the beginning of Benediction.
Adoremus in Aeternum is usually sung at the end.