1.Modal verbs: "They must be able to convey complex concepts" uses the modal verb "must" to express necessity, demonstrating the teacher's essential qualities.
2.Infinitive phrase as an adverb: "to ensure comprehension" uses an infinitive phrase to explain the purpose of simplifying language, adding depth to the sentence.
3.Present participle as an adjective: "employing interactive teaching methods" uses the present participle "employing" as an adjective to describe the teaching methods, enhancing the sentence's complexity.
4.Noun phrase as subject: "Adaptability to various learning styles" serves as the subject of the sentence, showcasing a complex noun phrase to describe a key quality of a good teacher.