The context of the sentence shows the dog is excited and happy, as it wags its tail in anticipation. "Eagerly" means with excitement or enthusiasm.
The subject "girl and her friend" is plural, so the verb "play" correctly agrees in number.
The passage focuses on how plants and animals have developed adaptations to survive the desert's harsh conditions, which is the main idea.
"Therefore" is the appropriate transition word to show a cause-and-effect relationship between forgetting to set the alarm and being late for school.
The correct pronoun to use as the subject of a sentence is "I." The phrase "Sarah and I" is grammatically correct.
