一、may well

may well 主要用於加強推測的語氣，表示具有較大的可能性。如：

It may well be true. 那很可能是真的。

What you say may well be true. 你說的很可能是事實。

Her grandpa may well be over eighty. 她的祖父可能已有80多歲了。

That may well have been their intention. 這很可能是他們的意圖。

【注】may well 中的 may 也可換成 might 或 could，但語氣更不確定。如：

He might well lose his job. 他多半會丟了那份工作。

He might [could] well find that the course is too difficult. 他很可能覺得這門課太難。

二、may as well

may as well 主要用於表示提議或勸告，意為“不妨”。如：

I may as well start at once. 我還不妨馬上就動身。

If that is the case, I may as well try. 既然如此，我不妨試一試。

Now that you have come you may as well stay. 既然你來了，你就留下。

【注】其中的 may 也可換成 might，但語氣更不確定。如：

He may [might] as well come with me. 他還不妨跟我一起來。

It’s not very far, so we may [might] as well go on foot. 那地方不太遠，所以我們還是走著去吧。

三、一點提醒

當表示提議或勸告時，may as well 與 might as well 意思相同，但是 might as well 還可將一種不愉快的情況同另一種不愉快的情況作比較，含有抱怨的意味，通常譯為“還不如”，此時不能用 may as well。如：

This holiday isn’t much fun; we might as well be back home. 這個假日過得真沒意思，我們還不如待在家裡。

“What a slow bus this is!” “Yes, we might just as well walk.” “這輛公共汽車開得多慢啊!”“是呀，我們還不如走著去。”

You never listen—I might as well talk to a brick wall. 你一點也不聽——我還不如跟牆壁說話呢。

The buses are so expensive these days, so you might as well get a taxi. 最近公共汽車車費很貴，還不如坐計程車去。