是each person's opinion吗 opinion要用单数还是复数

in my opinion 中opinion要加s吗 people's opinion varies from person to person.这句话有错吗? opinion 是to my opinion 还是 in my opinion 是 in my opinion 还是 on my opinion the children each是单数还是复数 "in my opinion"中的opinion可以加s吗 each family 谓语用单数还是复数 EACH后动词用单数还是复数? each student单数还是复数 person用于复数吗?no后加单数还是复数? 可以说“agree with one's opinion”吗?