Write the plural forms of the following nouns:

shelf, photo, herp, cactus, poster, child, music, formula, series, mathematics, jeans, glasses, clothes, hair, person, convenience, motto, water, item, box, body

ответ:

shelfs, photos, herpes, cactuses, posters , children , musics, formulas, series, mathematics, jeans, glasses, clothes, hair, people, conveniences, mottos, water, items, boxes, bodies

do you know the wilsons? they*re a very friendly family.

определенный артикль the ставится перед именами собственными (фамилиями), обозначающими целиком всю семью. 

isn't it

aren't you

did they

wasn't it

won't she

were they