4. Had the patient followed the doctor's advice, he would have recovered long ago.(過去時）

(=If the patient had followed the doctor's advice …）

要是病人當初能聽從醫(yī)生的勸告，他早就恢復健康了。

5. The patient must be instructed that, should his condition not improve within 48 hours, or deteriorate within this time, he should seek medical advice without further delay.(將來時)

(=The patient must be instructed that, if his condition should not improve...)

必須囑咐病人，萬一病情在48小時內未見改善或有所惡化，應立即就就醫(yī)。6. The heart would very soon fail if the stream of blood which furnishes its muscle with oxygen and nourishment, should dry up. （將來時）

如果給心肌提供氧氣和養(yǎng)料的血液干涸，心臟很快就會衰竭。

虛擬條件句還可用 if it were not for(現在時）或if it had not been for(過去時)這種句型來表示，意為“要不是”“若沒有”（相當于短語介詞but for)。其中連詞if可以省略,但必須使用倒裝結構，即were it not for 或had it not been for,將來時虛擬條件句的謂語也可用were to十動詞原形。 舉例如下：

7. If it were not for the science of blood transfusion, many thousand people would have had little chance of recovery. (現在時）

如果沒有輸血這門科學，成千上萬的人就很少有康復的機會。

8. The patient would have died of gastric cancer had it not been for the timely operation.(過去時）

(=…if it had not been for ...)

要不是及時手術，患者就會死于胃癌。

9. Were it not for the modern equipment, such operations would not be performed. (現在時）

(= If it were not for the modern equipment,…）

要是沒有這種現代化設備，這些手術就無法進行。