can的過去式英文

　　This could cause serious damage to the country's economy.

　　這可能對國家的經濟造成嚴重破壞。

　　The database could be used as a teaching resource in colleges.

　　資料庫可以用作大學裡的一種教學輔助手段。

　　I think we could all use a drink after that!

　　我想我們在事情辦完之後都得痛快地喝一杯。

　　He could just make out three people through the mist.

　　透過薄霧他勉強能看出有三個人。

　　The operation could prolong his life by two or three years.

　　這次手術可使他多活兩三年。