How can you determine if a verb is regular or irregular? a.

Check the past form.

b.

Check the base form.

c.

Add the helping verb be.

d.

Add-ing.

a check the past form

Explanation:

I might be wrong but it makes the most sense

by checking the past form

I would use the book , encyclopedia , computer for the sources. I would locate them by which is which source it categorizes . the type of the sources would make them authoritative sources. with the citation ,  authors name , credibility. also work habits.