主语从句中的虚拟语气
在it is adj.这样的句型中,当描述主语的表语形容词是 advisable,critical,crucial,desirable,essential,imperative,important,incredible,inevitable,necessary,recommend,strange,urgent等形容词时,主语从句的谓语动词多用虚拟语气,如果是现在时,谓语动词用should/would 动词原形(should/would经常省略);如果是过去时,则用should/would have done的形式。
▶It was inevitable that this primacy should have narrowed as other countries grew richer. Just as inevitably,the retreat from predominance proved painful.(随着其他国家日益富裕,美国的这一优势地位逐渐下降是不可避免的。惟其不可避免,从优势地位上退出愈发痛苦不堪。)
▶解析:这是一个含有主语从句的复合句。句首的It是形式主语,真正主语是that从句,该主语从句使用了虚拟语气should 完成时。