语法总结
真实条件句与危险后果
If explosives are used, vibrations will cause... 是真实可能性条件句。
相似句：
- If you press this button, the machine will stop.
- If it rains, the match will be cancelled.
与事实相反的虚拟语气
If there had not been... they would have completed... 写出救援本可更快完成。
相似句：
- If the road had been clear, we would have arrived earlier.
- If she had known, she would have helped.
If they knew... they would lose heart
这是与现在事实相反的虚拟语气，用来说明为什么要隐瞒困难。
相似句：
- If he knew the truth, he would be upset.
- If they understood the risk, they would refuse.