狀語從句中的虛擬語氣
if you phoned him right now, you might get the matter settled. 如果你現在給他打電話，你就可以把問題解決了。
there could be something wrong with the tape recorder. 這臺錄音機可能出毛病了。
he might have said so. 他可能這樣說過。
could he have done such a foolish thing 他會做這樣的傻事嗎？
2.表示委婉或客氣
虛擬語氣（could, would, might + 動詞原形）可使說話者的口氣變得委婉客氣。
you could answer this email for me. 你可以替我回這個電子郵件。
could you leave me your telephone number and address 你能將電話號碼和地址留給我嗎？
would you mind opening the window 勞駕把窗子打開，好嗎？
you might as well put off the discussion till next week. 你們不妨把討論推遲到下個星期。
比較：
would lide to do
愿意，想要
would lide to have done
本來想
i would like (to have) a word with you.我想和你談一談。(現在想)
i would like to have talked with you.我原本想和你談一談的。（沒有談成）
3.表示惋惜或責備
given more time, we could have done better. 如果給我們更多時間，我們能夠干得更好些。（我們并沒有得到更多的時間）
you could have got up a little earlier！ 你完全可以早點兒起來！（實際上沒有早起）
it was cold yesterday. i should have worn a heavy coat. 昨天很冷，我該穿件厚外套的。（但我沒穿）
this wall shouldn't have been pained blue. 這墻不應該漆成藍色。（但已漆了）
提示：
當代英語一個顯著的變化就是虛擬語氣的使用越來越少，許多該用虛擬語氣的地方都用陳述語氣代替。
he suggested that i went to the hospital at once. 他建議我們立刻去醫院。（原應用should go）
we shall write down the address lest we forget. 我們要把地址記下來，以免忘記。（原應用should forget）
imagine you are an astronaut. 設想你是個宇航員。（原應用were）