In this case, the Noun is singular (roof), so that the pronoun is singular. Several is always plural, so we can use the general pronoun of plural. Everyone is the forerunner, and it`s always unique, so you need a singular pronodem. We use her or her as a male or female is not specified. Someone is the forerunner and is always treated as a singular, so he needs the singular pronoune. As no sex is known, we use it. The precursor is not (no boys) and it is not always singular, so it has a singular pronodem. It is his (not her) because it concerns only men. Each one is always unique, so has a singular pronoun. It is not him or her, because they are used as an object. It must be him or her. Some (like all, most, many, and none) may be singular or plural, depending on the noun in the preposition sentence (children).
In this case, the children are plural, so the pronoun is plural. It is also the possessive pronoun, that is, the mothers of children. No one can be singular or plural depending on the name in the prepositional sentence (the pilot). As it is plural (pilot), the pronoun is the plural (possessive). In this pronoun agreement quiz, you are tested on certain types of words, English learners find it very difficult, and often make mistakes with. Here are some of the words: one is the subject and is unique. And its regarding a male (uncle) it`s his.