Arabic and Hebrew use this type of copula in sentences lacking a word for "to be."
In Proto-Indo-European studies, this kind of ablaut contrasts with both the "e-grade" and "o-grade" varieties. In English syntax, this form of complementizer is inherent to the sentence "I think they like me." This type of "derivation" is exemplified by using a noun such as "pen" as a verb, as in "I penned it." In the Chomsky hierarchy, unrestricted grammars are also called "Type-[this]". Arabic and Hebrew use this type of copula in sentences lacking a word for "to be." In linguistics, this term also denotes an inferred word or part of speech that isn't outwardly expressed. For 10 points, identify this number word which the Mayans wrote as a shell glyph before medieval Europeans started using it in calculations.
In Proto-Indo-European studies, this kind of ablaut contrasts with both the "e-grade" and "o-grade" varieties.
zero [or null; or 0; or zero-grade ablaut; or zero conjunction; or zero complementizer; or zero derivation; or Type-0 grammars; or zero copula; accept any of the above answers with null in place of "zero"]