Why have [used] "attendance" and "enrollment" been used but not "the attendance" and "the enrollment"?
Why [have] has the author
used "attendance" and "enrollment" but not "the attendance" and "the enrollment"?
This provides a good example of when English speakers would use the passive, Ori. The focus is on the action, not on the obscure writer/speaker.
however MIT stated that the only record it has of attendance by a student with Li’s name was [an] enrollment in a “non-degree short course”
I'd say because it's more general than specific. Note the specificity in 'the only record' but MIT can't state for sure that that particular student, [a
student was the Li Xiaolin in question.
Note the 'an' I've added to 'enrollment'. I've done this not to suggest that it's natural or likely, but merely to show that the issue is not yet a specific one, which could engender the use of 'the'.