Subjunctive Mood.
Simply, the Subjunctive Mood supposes or wishes.
A few models.
If you could come, we would be so glad.
Should you have to go to town, you might post this for me.
[Should have to = "should be required to". You might = please.]
“Sometimes I wish I could turn back time”
Homework.
Find/note/figure out Subjunctive Mood whenever/wherever it is used.