To answer this question concerning Robert Stam's Introduction: The Theory and Practice of Adaptation, look carefully at the progression of his ideas concerning film adaptations; doing this will help you explain the text and elucidate its main points.
First, note that Stam engages in a discussion about the biases many have held against film adaptations of literary works. Stam discusses different sources of hostility toward the practice of adaptation. He mentions that many have long viewed literature as being superior to film and have positioned the two mediums as if they are diametric opposites. He also elaborates on how iconophobia, logophilia, anti-corporeality, the myth of facility, class prejudice, and parasitism play a role in generating mass resistance against cinematic adaptations of various literary works. Think about why Stam expounds on these various hostilities toward film adaptations. By describing these hostilities, what issue or set of issues does Stam shed light on?
Second, note that Stam, after talking about the prejudices people have held against film adaptations, highlights what film can accomplish that literature cannot. He states that film can capture the sonic nuances of speech as well as a variety of nonverbal cues such as eye contact, facial expressions, and body language. He also states that, while a literary work only consists of characters, a film consists of characters and performers, allowing an audience to not only dissect the actions of a film's characters but also examine the performances of its actors. Think about how Stam's revelation of the film medium's accomplishments supports his main points.