This document discusses how TOEFL questions test the use of prepositions. It notes that prepositions can have literal or idiomatic meanings, and the TOEFL often tests the idiomatic use. It provides examples of incorrect prepositions, such as "called on" instead of "called off" and "count in" instead of "count on". It also gives examples of sentences missing prepositions, like "wait me" instead of "wait on me" and "plan attending" instead of "plan on attending". The document emphasizes being able to identify both incorrect prepositions and missing prepositions in sentences.