Resolved questions
What is the difference between using 凡 and 一切，所有 and 都？

凡 in general,has two usings: 1. 凡是: its meaning is similar as "as long as" eg:凡是小孩子，都喜欢玩。 2.凡事：means all tings eg.: 凡事都要想清楚
所有=一切，and both of them are adj.,but in general, we dont use 一切 in front of "people", but we can say所有人，所有朋友
都 is often used as adv. e.g.: 所有同学都来了