The infinitive phrase in this sentence is to speak clearly, and it is used as a subject of the sentence. What/who is essential to being understood? To speak clearly.
1. Personification. Chimneys do not have legs, nor do they bounce on fours. The act of personifying is to give a non living item human qualities.
2. Metaphor. The sentence is comparing a bridge to an eye without the use of like or as.
3. I’m not sure on this one. Maybe metaphor (glass bowl to a hill).
4. Likely a simile. This sentence is comparing the bride to a fan while using like.
