有一例题不懂 This exercise is too difficult for anyone of us to do

有一例题不懂 This exercise is too difficult for anyone of us to do it.为什么改成any of us 就可以 原来错哪里
顺便区分下anyone of us ,any of us ,any one of us的区别

anyone后面不能接of
any one比anyone更强调“个别”的意味；anyone则含有“全体”、“毫无例外”之意.
至于any 与 any one,any既可以用于指代整体,也可以用于指代个体；显然any one是指代个体嘛
any
形容词 a.
1.任一,每一
He wanted a job,any sort of a job.
他需要一个工作,任何工作都行.
2.(一般用于疑问句,否定句,if从句中)若干,一些;一点,丝毫
If there is any trouble,do let me know.
如遇到麻烦,务必告诉我.
I haven't any money to spare.
我的钱都用光了.
Are there any letters for me?
有我的信吗?
3.尽可能多的;所有的
Send me any data you can find.
把你能找到的所有资料送来给我.
代词 pron.
1.任何一个;任何人
Richard is taller than any of us.
理查德比我们当中任何人都高.
2.若干;一点
Give me some if there is/are any.
如有,给我一些.
副词 ad.
1.(用于疑问句,否定句,if从句中)少许,稍微
Don't go any closer.