Hello. You did not provide the phrases that the questions refer to, but I can help you by showing you a way to answer them. I hope it helps you.
1. You may find that the underlined phrases are adjectives if they are showing the characteristics of something or someone. You can see that the sentences are nouns if they are naming something or someone. In addition, you may find that underlined phrases are adverbial if they are modifying a verb or a name, for example: "The popcorn was too salty", where the underline phrase modifies the name popcorn and represents an adverbial phrase.
2. When a word is underlined it means that the author of the sentence wants to highlight the meaning of that word within the text. In other words, we can say that the author wants to emphasize that word, give importance and draw attention to what it represents.
3. Words in boxes are generally used to indicate automatic examples in internet articles and to include a link that can lead to another related article what the word means.
4. Plural words are those that indicate more than one being, object or represent a group of the same beings or objects, such as "dolls", "bees", "vases", "women". The words in the singular, on the other hand, are words that represent only one being or object such as "books", "car", "bird", "mug".
5. The subject is the element in the sentence that is suffering from the action of the verb, which shows that subject and verb have a strong relationship with each other and therefore they must combine and agree on number and gender. For example: In the phase "The cell phone rang all morning" the word "rang" is the verb, who is suffering the action of the verb, that is, who was ringing was the cell phone, so "cell phone" was the subject of the sentence. In addition, cell is a singular word, so the verb must also be singular.
