1. 将条件隐含在不定式短语中
I should be happy to go with you. 如果能与你一起去，我将很高兴。(=I should be happy if I could go with you.)
To have studied harder, you would have passed the examination. 你学习更用功些，你早就考及格了。(=If you have studied harder, you…)

2. 将条件隐含在分词短语中
Born in better times, he would have been a scholar. 如果出生在好时代，他早就成为学者了。(=If he had been born in better times, he …)
Failing this time, what would you do？ 假若这次失败，那你怎么办？(=If you failed dthis time, what…)
Walking alone in the dark, Mary would be terrified. 要一个人单独在黑暗中走，玛丽会感十分害怕。(If Mary walked alone in the dark, she…)

3. 将条件隐含在介词短语中
Without air, no one could live. 没有空气，人就不能活。(=If there were no air, no one could live.)
But for his help, he would have failed. 要不是有他的帮助，他就会失败了。(=It it hadn’t been for his help, he would have failed.)

4. 将条件隐含在名词短语中
A true friend would not have betrayed me. 若是真正的朋友，就不会背弃我。(=If he had been a true friend, he would…)
A few hours earlier, and you would have seen the famous writer. 要是你早来几个小时，你就见到这位著名的作家了。(If you had come a few hours earlier, you…)

5. 将条件隐含在某些连词中
I didn’t know that he was a cheat, or else I wouldn’t have believed him. 我不知道他是个骗子，不然我也不会相信他了。(or else=if I had known he was a cheat)

I’m really very busy, otherwise I would certainly go there with you. 我真的是太忙了，不然我就会同你一道去了。(otherwise=if I were not so busy)

6. 将条件隐含在定语从句中
Anyone who had seen that painting might have taken it for a photo. 凡是看过那画的人，都可能把它看成是照片。(=If anyone had seen that painting…)

7. 将条件隐含在一定的上下文中
Don’t bother to read all these papers. It would take too long. 不要费事看所有这些文件了，那会花太多时间。(=…If you read all these papers, It would take too long)