2 and 2 are four.5 plus 5 is ten.请问这两句话为何一个用is另一个用are?“等于”英文

and ------用 are （and 是并列连词,成分并列的,可共同做主语）
plus ------用 is （plus 是介词,plus 5 ,介词不能做主语成分）
就像and 和with 的用法一样,因为with也是介词,不能做主语成分
Jack with his sister goes to school every day,
Jack and his sister go to schol every day