– I think we can have a long time to relax this summer!–. We should get ready for high sch

问题补充：

– I think we can have a long time to relax this summer!

–. We should get ready for high school.

A. I think so

B. I disagree

C. That sounds good

D. Good luck

答案：

A. I think so

(答案→)B. I disagree

C. That sounds good

D. Good luck

解析：I think so我是这么认为；I disagree我不同意；That sounds good听起来不错；Good luck祝你好运。句意：我想这个夏天我们要有很长一段时间休息了。根据下文，我们应该为高中生活做好准备。可知选B，最符合语境。