will 和 be going to 都能表将来，什么时候能互换、什么时候不能，是中考单选的经典辨析点。这篇把三种将来表达的结构、语气和标志词一次分清。
三种将来表达对比
| 表达 | 结构 | 侧重 | 例句 |
|---|---|---|---|
| will | will + 动词原形 | 临场决定、承诺、预测 | I will help you with your English. |
| be going to | am / is / are going to + 原形 | 事先计划、有迹象的推测 | We are going to visit the museum this weekend. |
| 现在进行时表将来 | am / is / are + doing | 已安排好的近期行程（位移动词） | We are leaving for Beijing tomorrow. |
will 句型的变化与常用结构
- 肯定：I will call you tonight.
- 否定：It won't rain tomorrow.（will not 缩写 won't）
- 疑问：Will you come to my party? 回答 Yes, I will. / No, I won't.
- There be 的将来：There will be more trees in five years.
- 标志词：tomorrow、next week、in two days、soon、this evening
注意：在时间状语从句和条件状语从句里不用 will——When he comes back, I will tell him. 主句用将来，从句用一般现在时。
辨析：will vs be going to
两者常可互换，但语气不同：will 强调说话时才做的决定或承诺——The phone is ringing. I will answer it（听到铃响才决定去接）；be going to 强调事先已计划，或眼前有迹象——Look at the black clouds. It is going to rain（乌云是迹象）。考题给出迹象（乌云、要迟到）时选 be going to，给出响应式场景（我帮你、我马上来）时选 will。