语法总结
if 真实条件句
If she comes, she will get... 用一般现在时表达条件，主句用 will 表结果。
相似句：
- If he comes, we will help him.
- If you work hard, you will improve.
过去完成时表示先发生
Work had begun before my sister left 表示动工先于姐姐离开。
相似句：
- The film had begun before we arrived.
- He had left before the storm came.