在英语中，混合条件句（mixed conditionals）或错综条件句通过不同的时态，来谈论与过去相反的情况所导致的现在可能发生的结果。这类句子的结构看似复杂，但如果理解了主句和从句之间的关系，就不难掌握它的用法。
 
Hi! I'm Georgina from BBC Learning English. In today's lesson, we're looking at mixed conditionals.
We usually use mixed conditionals to talk about a past imaginary situation that has a present imaginary result.
For example: If I had eaten breakfast, I wouldn't be hungry now.
The first phrase uses the same structure as the third conditional – if + past perfect. This is because it is a past imaginary situation. It's not true. I didn't eat breakfast.
The second phrase uses the same structure as the second conditional – would + infinitive (no to). This is because it is a present imaginary result. It's not true. I am hungry because I didn't eat breakfast.
Don't forget to put the comma in after the 'if' clause.
Bye for now!
 
用法总结
混合条件句的前半部分结构为 “if + 过去完成时”，用来提出与过去事实相反或不符的情况；后半部分结构为 “would + 动词原形”，引出若之前提出的假象条件成立，现在可能发生的结果。注意，“if” 从句在前时，从句后加逗号；“if” 从句在后时，不加逗号。
If I had eaten breakfast, I wouldn't be hungry now. 
（实际上之前没有吃早饭，所以现在很饿）
If he had studied harder, he would have a better job.   
（实际上之前没有努力学习，所以现在的工作一般）
She wouldn't be late for the meeting if it hadn't been raining so hard.
（实际上之前雨很大，所以没能按时到达）