walk on the grass.是祈使句.改成否定句为Don't walk on the grass.
there is a park in our city.改为一般疑问句Is there a park in our city?
i often watch socer matches去掉often改成现在进行时:I am watching socer matches.
It'sunny,and it's hot there的汉意:那里天气晴朗,而且很热谢谢，3Q！！！