2019高考二輪復(fù)習(xí)英語教案: 情態(tài)動詞和虛擬語氣
②it's time to do something有別于it's time that...
4. 比較if only與only if
only if表示"只有"；if only則表示"如果……就好了"。if only引起的句子，一般過去時或would+動詞原形表示現(xiàn)在或未來事實相反，過去完成時表示與過去事實相反，也可用于陳述語氣
i wake up only if the alarm clock rings. 只有鬧鐘響了，我才會醒。
if only the alarm clock had rung. 當(dāng)時鬧鐘響就好了。
if only he comes early. 但愿他早點(diǎn)回來
if only we knew where to look for him. 我們要是知道到哪里去找他就好了
if only i had listened to my parents. 要是我聽取了父母的話該多好啊
5. but 或 but that 表達(dá)的含蓄條件的特殊含義
but 或 but that 做“如果不……”解，意思相當(dāng)與“if not”，其后面不可接虛擬模式，應(yīng)接陳述式的現(xiàn)在時動詞或過去時動詞，即‘but that + 主語 + 現(xiàn)在時動詞 / 過去式動詞’，而主句要用虛擬式。
but that you help him , he would fail . 如果沒有你的幫助，他會失敗的
but that you helped him , he would have failed . 如果沒有你的幫助，他早就失敗了
6. need “不必做”和“本不必做”
didn't need to do表示過去不必做某事, 事實上也沒做；needn't have done表示過去不必做某事, 但事實上做了
john went to the station with the car to meet mary, so she didn't need to walk back home.
約翰開車去車站接瑪麗，所以她不必步行回家了
john went to the station with the car to meet mary, so she needn't have walked back home.
約翰開車去車站接瑪麗，所以她本不必步行回家了。 （mary步行回家了，沒有遇上john的車 ）
【典型例題】
there was plenty of time. she ___.
a. mustn't have hurried b. couldn't have hurried
c. must not hurry d. needn't have hurried
【解析】 d needn't have done. 意為"本不必"，即已經(jīng)做了某事，而時實際上不必要。mustn't have done 用法不正確，對過去發(fā)生的事情進(jìn)行否定性推斷應(yīng)為couldn't have done, "不可能已經(jīng)"。must not do 不可以（用于一般現(xiàn)在時）
7. 不定式的完成時用在 intend , mean , plan , suppose 等動詞后，表示原打算做而實際未能做而實際未能做成的事，因而含有虛擬的意思
8. need / needn’t + have done 結(jié)構(gòu)也可以表示虛擬語氣，作‘本來有/沒有必要做某事’
9. as it were 常插在句子中，表示‘姑且這樣說，可說是’這類的意思
he is a grown-up baby, as it were . 他可說是一個大孩子了
he became, as it were a kind of hero from a strange land. 他仿佛成了一個來自異鄉(xiāng)的英雄
he was, as it were , intoxicated by the soft air and sunshine of spring. 他可說是被春天的和風(fēng)和陽光陶醉了
10. would think 本身就是虛擬語氣，表示會認(rèn)為，想到.