一般说来，英语中的虚拟条件从句（Sentence of Unreal Condition）是用if引导的从句表示，但有时也可用其他方式来暗示存在虚拟条件。这种隐含式虚拟条件句叫含蓄虚拟条件句，它常可以转化成if引导的虚拟条件句，常有如下一些表达方式。
一、用介词或介词短语表示
常见的介词和介词短语有without、with、under、in、but for、in the absence of等。
We wouldn’t have achieved so much without the correct leadership of the party．（=if there hadn’t been the correct leadership of the party）．如果没有党的正确领导，我们就不会取得这么大的成就。
With better equipment（=If we had better equipment），we would have finished the job ever sooner．要是设备好些，我们本可更快地完成这项工作。
But for the traffic jam（=lf it hadn’t been for the traffic jam），we would have arrived long ago．要不是交通拥挤，我们早就到达这儿了。
Under another social system（=If it had been under another social system），such floods would have caused terrible disasters．要是在另一种社会制度下，这样的水灾是会造成可怕的灾难的。
In doing so like that（=If I did so like that），my teacher might be angry with me．如果像那样做，老师也许会生气的。
