A pattern of accidents,of personnel problems,adn of low performance ratings for mechanical systems have marked the servicing and maintaining of the new power plant
(B)have marked the service and maintenance
(E)has marked the servicing and maintenance
答案是(e)
我的問題
1.為甚麼動詞不是複數
我認為 A pattern就像是提公因數一樣,所以總共是三個pattern
2.serving and maintenance應該不是對稱的,未何答案是選擇(E)呢?
謝謝各位解惑[/u]