The Bound Morpheme "ing" is a Marker that identifies "to be" as an Progressive Aspect Auxiliary and NOT a Verb.
In the sentence "I am going," the word "am" is NOT the copula but an Auxiliary, specifically called the Progressive Aspect.
How do we know when it is or is not the copula? If you look at the Verb "go," you note it has an "ing" ending. This bound morpheme is a Marker, which identifies "am" as as the Progressive Aspect auxiliary.
Remember we talked about Markers on slide 14 entitled: "Bound Morphemes are used to change the function of some words and to identify the function of some others."
So here is a short quiz for you. Which of the following sentences contains the auxiliary?
- "I am sick of you."
- "I am sicking my dog on you."
- (Answer--The second sentence)
There is also a Perfect Aspect--the auxiliary word "to have." In the example, "I have jumped," the "ed" is the marker that identifies "have" as the Perfect Aspect Auxiliary and not a verb.