I believe the answer is introductory.
1.Commerce....formal
2.What's up....informal
3.May be....informal
4.Thanks...informal
5.Patrons...formal
6.Banquet....formal
7.Grant....formal
8.Do you fancy...informal
9.Engage....formal
10.Say grace....informal
11.Presence....formal
12.Resume....formal
<span>13.Apprehended....formal</span>
The literary term for this is mood
