for the weekend和at the weekend有啥区别呢,

这 个其实就是介词的区别了
What are the johnsons going to do at the weekend?
詹森打算在周末干些什么～（at是指的时间点～,指的在周末～)
We're going to stay at my mother's for the weekend.
我们将在妈妈家里度过这个周末～(for 是指的一段时间,指的持续性的时间,延续了这个周末～）
我再写点例句～
We usually do our shopping at the weekend.
我们通常利用周末采购物品.
Could we go and play tennis at the weekend?
能一起去打网球吗?
We slipped away to Paris for the weekend.
我们赶到巴黎去度周末
Do you have any plans for the long weekend?
你有办法打发这个漫长的周末吗?