why don't we go to the beach?怎样回答

That is a good idea!
这种情况会出选择题,有几个较易混淆的选项,在这里列出 as follows：
That's right意思是“对了”,表示赞同对方的意见、看法或行为,肯定对方的答案或判断,其相反说法是That's wrong.而That's all right意思是“没关系,不用谢”,用作回答对方的道歉或感谢.All right的意思是“行,可以,好吧”,表示同意对方的意见或要求.D,意思是不用谢.thank you very much.that's ok.