The cat's eyes are green
答：少了句号.
改：The cat's eyes are green.
It's ten to nine p.m John is in Suzhou ,he is studying English now
答：少了句号.两句之间用and并列,或用分号也可以,逗号不能连接两个句子.
改：It's ten to nine p.m.John is in Suzhou.He is studying English now.
或：It's ten to nine p.m.John is in Suzhou and he is studying English now.
或：It's ten to nine p.m.John is in Suzhou ; he is studying English now.
John usually study English at nine o'clock in the evening
答：少了句号.主语为第三扔称单数时,一般现在时,谓语动词用S形.
改:John usually studies English at nine o'clock in the evening.
Beijing is the capital of China
The book is not hers
答：少了句号.
改:Beijing is the capital of China.
改:The book is not hers.
Are these books yours?
对!
I will come here this week
答：1.少了句号.
2.时态与时间状语this week 不配.这个星期,包括周一到周日的时间.不是纯将来的时间,有纯将来时态不妥.
3.这个come here 用在“我”上,不合逻辑.因为你就在这儿,还说将来这儿吗?
改：I will come here again next week.下个星期我还要来这里.
楼上的几位是在鼓励你.其实,标点符号,大小写也是很重要的,有时,不同的标点,大小写的不同,会有不同的意思,这也是语法.从一开始就要注意.