could的用法

看到一段標題

"Microsoft Office for iOS, Android could debut early next year""A version of Office for the iPhone, iPad, and Android devices will launch in early 2013, according to the Verge."

雖然原文標題我大概看得懂是
"iOS及Android版本的 Office 可能明年初會上市"

原文:
http://news.cnet.com/8301-10805_3-57546259-75/microsoft-office-for-ios-android-could-debut-early-next-year/


因為最近看到有關could的用法

1.can 的過去式

2.禮貌的請求
"could you operate this washing machine for me?"

3.和現在或未來事實相反
"If I had enough money, I could buy  that car now."


以前我如果看到could就很單純的翻譯成"可能"....但自從學了假設語氣後,每回看到could/should...這類東西腦袋都會卡住

另外我也看過有書上寫
可能性的強度 =>"can>may>could>might"

如果could都已經被認定為是"和現在或未來事實相反" 那 could怎麼還會比might排序在前面??

我目前的猜測是=>是否could出現在 "if"子句才是 "和現在或未來事實相反"?????