Do you think it important for us to plant trees?（改为同义句）Do you think -- -- -- --for us to plant trees

Do you think it important for us to plant trees?（改为同义句）Do you think -- -- -- --for us to plant trees
Do you think it important for us to plant trees?（改为同义句）
Do you think -- -- -- --for us to plant trees

Do you think it important for us to plant trees?（改为同义句）Do you think -- -- -- --for us to plant trees
Do you think it is of importance for us to plant trees ?

一共是4个空格吗？那么试试这个？
Do you think that it is important for us to plant trees?
可以理解成，第一句中it代替主语,第2句句中由that引出后面的从句。
good luck ^^

Do you think it is of importance for us to plant trees

Do you think that planting trees is important for us ?