书本上有几题目文法不太会麻烦会的帮我解疑惑谢谢

书本上有几题目文法不太会麻烦会的帮我解疑惑谢谢
Q1.
This city has six hundred thousand people.
PEOPLE可不可以换成POPULATION阿?
意思还是同等么?
Q2.
Christmas comes on the twenty-fifth of Decomber.
为什么要用come on?
Q3.
I am now in the third year of the junior high school.
1.now副词可否放到句首或者句末?
2.year为什么不用复数
Q4.
My books are twice as many as his.
比较这两个
My books are double as many as his.
My books are the double of his.
文法有错误麼
差别请问在哪0.
Q5.
He earns over 800 dollars a week.
这句话 ...
我后面换成 every week跟原来有差别么?
Q6.
书上这句话
Give me two dozen of eggs.
有加上 of 那个听说是错误的是么?
Q7.
(选哪个好才比较好A/One) hundred dollars was a large sum to me.
Q8.
Six mounths(is,are)not very long.
我填are为什么错呢?
Q9.
He found is difficult at first,but soon got used to it.
这题要怎翻译@@?