Q：一本修辭書籍說，在 The house was set on fire and seriously damaged last night, but the perpetrator was unknown. 這句中，第二個 was 不可省略。但根據文法規則，這個 was 不是可以省略嗎?

A：「省略」(ellipsis) 是英文的主要特色之一，雖然「當省則省」、「能省就省」，但若省過頭就不合語法了。The house was set on fire and seriously damaged last night, but the perpetrator was unknown. (房子昨晚遭縱火而嚴重損壞，但兇手身份不明) 這句前半部中的 was 是個助動詞，因為它是被動結構，而後半部中的 was，則是個連綴動詞，所以兩者的功能或用法並不相同，當然不能省略。同樣地，在 The president was killed in a car accident, but his death was highly welcome in his country. (總統在車禍中喪生，但他的死卻受到該國多數人額手稱慶) 這句中，第二個 was 也不能省略。