A：may/might well 意為「很可能；儘可，有足夠理由」，如 She may/might well refuse to speak to you. (她很可能拒絕跟你說話)；You may/might well say so. (= You have good/enough reason to say so.) (你有足夠的理由這麼說)。這種句型也可變成倒裝句，如 She may well refuse to speak to you. 可以變成 Well may she refuse to speak to you. — 請注意詞序。再舉一例：Well may you ask why! (你儘可以問原因啊)。
再者，你可能會見到 might well + have + P.P. 的句型，這僅意為「很可能」，它的用途主要有二：(1) 在與過去事實相反的假設語氣中用於結果子句，如 We lost the baseball match, but we might well have won if one of our players hadn’t been hurt. (我們輸了這場棒球賽，但如果我們有個球員不受傷的話，我們很可能會贏)；(2) 對過去所發生事情的推測，如 Your mother might well have been looking for you. (你媽媽很可能一直在找你)。注意：在否定句中，NOT 是位在 “well” 之後 (意為「很可能不」)，如 You may well not recognize him. (你很可能認不出他了)。
may/might (just) as well (= had better/best) 意為「最好 (還是)；還是…的好」，如 You may/might as well not fool around all day long. (= You had better/best not fool around all day long.) (你最好別整天遊手好閒) — NOT 同樣位在 “well” 之後 (意為「最好不」)；No one will eat the food; it may/might just as well be thrown away. (沒有人要吃這些食物，最好還是扔掉算了)。
may as well A as B 意為「與其 B 不如 A」。
might as well A as B 意為「做 B 等於做 A」。例如：
- One may as well not know a thing at all as know it imperfectly. (與其一知半解不如完全不知)
- We might as well negotiate with a tiger for its hide as try to make peace with the Chinese Communists. (與中共謀和無異於與虎謀皮)