work hard is of great important to us这句话中为什么有个of?

work hard is of great important to us这句话中为什么有个of? the news is of great important to us.of在这儿起什么作用,看着好变扭啊·· All of us found hard to work out the maths problem 为什么答案是it sleep is important to us这句话有两个问题 It is hard of us to learn/of us to learning/for us to to lea the important p__ is to work hard To study hard is the most important d____ of students. Energy is of great __(important) to humans Your job is of great _____ to our business. (important) the man is of great cost to me .这句话为什么要加 cost? reading is very important to all of us 翻译.! The news is of great importance to us.