⒈ 在表示願望的動詞wish後的賓語從句中,需用虛擬語氣.（wish後的that 常省略）,根據主句時態,從句謂語時態相應退後一位,例如：How she wished his family could go with him.
⒉ 在具有願望、請求、建議、命令等主觀意願的動詞(desire, demand, advice, insist, require, suggest, propose, order, recommend, decide …) 後的賓語從句中需用虛擬語氣.謂語動詞用(should) +動詞原形.值得注意的是,如果賓語從句的動詞是否定的,否定詞not的位置應在動詞之前,而不是動詞之後.例如：The head nurse insisted that the patient not be move.另外,如suggest表達“暗示”,insist表示“堅持某種說法”時,後面的從句不用虛擬語氣,例如：Her pale face suggests that she is ill.或He insisted that he did not kill the boy.
除此之外,上述動詞也要求用虛擬式
① 在It is+上述動詞的過去分詞,其後所跟的主語從句中,如It is suggested that pupils wear school uniforms.
② 在上述動詞相應的名詞形式作主語+連繫動詞,其後的表語從句中,例如His suggestion was that classed be re-scheduled.
⒊ would （had）rather , would sooner也用來表達主觀願望,它們之後的賓語從句中需2 2.用虛擬語氣.謂語動詞用過去式表示現在或將來,用過去完成式表示與過去事實相反,例如：I would rather he went right now.
其他形式的虛擬語氣
⒈ it is +necessary等形容詞後,that主語從句中虛擬形式使用,這類形容詞包括necessary, important, essential, imperative, urgent, preferable, vital, advisable等,例如It is necessary that you listen to the teacher carefully.或者It is essential that you be able to pronounce every single word correctly.
⒉ 在It"s (high/about) time 之後的定語從句中需用虛擬語氣.謂語動詞用過去式,例如It is high time that you went to school
⒊ 虛擬語氣在as if / as though 引導的方式狀語從句中的應用（謂語動詞形式與wish後的賓語從句基本相同）表示與現在事實相反或對現在情況有懷疑,謂語動詞用過去式.例如：He felt as if he alone were responsible for what had happened. 表示過去想象中的動作或情況,謂語動詞用過去完成式.
⒋ 在lest 引導的狀語從句中,謂語動詞多用虛擬語氣,(should )+ 動詞原形.例如： The mad man was put in the soft-padded cell lest he injure himself.（1998年1月四級第38題）
⒌ 在if only 引起的感嘆句中需用虛擬語氣.謂語動詞用過去式或過去完成式.例如： Look at the terrible situation I am in! if only I had followed your advice.
3.用以表示虛擬條件的虛擬語氣
⒈ 用if條件從句表示的虛擬條件,是虛擬條件最普通的方式.
① 虛擬現在時表示與現在事實相反的假設,其if 從句的謂語形式用動詞的過去式(be 一般用were),主句用would/ should/ could/ might +動詞原形,例如：If I were in your position I would marry her.
② 虛擬過去時是表示與過去事實相反的假設,if 從句的謂語形式用過去完成時即had＋過去分詞,主句用would / should / could / might + have +過去分詞,例如：If it had not rained so hard yesterday we could have played tennis.
③ 大多數的虛擬條件句屬於上面三種情況的一種,但並不排除存在條件和後果中,一個和現在情況相反,另一個和過去情況相反,例如：If you had followed what the doctor said, you would not have been so painful now.這個句子在高中出現頻率頗高.
④ 但是,如果後果用了虛擬語氣,而條件卻用陳述語氣,這種用法是錯的.
⒉ 除了表示虛假條件外,if從句還可以表示對將來的推測,由於是將來還沒有發生的,所以談不上是真實的還是虛假的,只能說這個事情發生的可能性有多大.一般情況下,可以用陳述語氣的if從句來表示對一個未來事實的推測,這個事實是完全可能發生的.If從句的謂語形式用一般過去式或用were to / should +動詞原形,主句用would / should /could/ might +動詞原形,例如：Jean doesn"t want to work right away because she thinks that if she were to get a job she probably wouldn"t be able to see her friends very often.（1996年1月四級第44題）
⒊ 有時可以把含有助動詞、情態動詞、be或have的虛擬條件句中的連詞if 省去,而將had , should, were 等詞提到主語之前,即用倒裝結構,這時候,如果出現not等否定詞,否定詞需放在主語後面.這種結構在口語中很少使用,但頻頻出現在各類考試中出現,例如：If it had not rained so hard yesterday we could have played tennis.→Had it not rained so hard yesterday, we could have played tennis.
⒋ 大多數的虛擬條件透過上面所講的兩種方法表達,但在個別句子中也可以透過介詞without和介詞短語but for表達,副詞otherwise等表達出來.例如：We didn"t know his telephone number; otherwise we would have telephoned him.（1995年6月四級第46題）值得注意的是,包含but for的句子,謂語動詞必定要用虛擬形式,但包含without等短語的句子,謂語動詞未必一定要用虛擬語氣.
⒌ 有時虛擬條件不是明確地表達出來,而在蘊含在用but引導的從句裡,於是便出現了有謂語動詞是虛擬語氣的主句加上謂語動詞是陳述語氣的but從句構成的並列複合句,例如I would have hung you but the telephone was out of order.在這樣的句子裡,如果主句沒有用虛擬語氣,或者從句用了虛擬語氣,都是錯的.
用在賓語從句中的虛擬語氣
⒈ 在表示願望的動詞wish後的賓語從句中,需用虛擬語氣.（wish後的that 常省略）,根據主句時態,從句謂語時態相應退後一位,例如：How she wished his family could go with him.
⒉ 在具有願望、請求、建議、命令等主觀意願的動詞(desire, demand, advice, insist, require, suggest, propose, order, recommend, decide …) 後的賓語從句中需用虛擬語氣.謂語動詞用(should) +動詞原形.值得注意的是,如果賓語從句的動詞是否定的,否定詞not的位置應在動詞之前,而不是動詞之後.例如：The head nurse insisted that the patient not be move.另外,如suggest表達“暗示”,insist表示“堅持某種說法”時,後面的從句不用虛擬語氣,例如：Her pale face suggests that she is ill.或He insisted that he did not kill the boy.
除此之外,上述動詞也要求用虛擬式
① 在It is+上述動詞的過去分詞,其後所跟的主語從句中,如It is suggested that pupils wear school uniforms.
② 在上述動詞相應的名詞形式作主語+連繫動詞,其後的表語從句中,例如His suggestion was that classed be re-scheduled.
⒊ would （had）rather , would sooner也用來表達主觀願望,它們之後的賓語從句中需2 2.用虛擬語氣.謂語動詞用過去式表示現在或將來,用過去完成式表示與過去事實相反,例如：I would rather he went right now.
其他形式的虛擬語氣
⒈ it is +necessary等形容詞後,that主語從句中虛擬形式使用,這類形容詞包括necessary, important, essential, imperative, urgent, preferable, vital, advisable等,例如It is necessary that you listen to the teacher carefully.或者It is essential that you be able to pronounce every single word correctly.
⒉ 在It"s (high/about) time 之後的定語從句中需用虛擬語氣.謂語動詞用過去式,例如It is high time that you went to school
⒊ 虛擬語氣在as if / as though 引導的方式狀語從句中的應用（謂語動詞形式與wish後的賓語從句基本相同）表示與現在事實相反或對現在情況有懷疑,謂語動詞用過去式.例如：He felt as if he alone were responsible for what had happened. 表示過去想象中的動作或情況,謂語動詞用過去完成式.
⒋ 在lest 引導的狀語從句中,謂語動詞多用虛擬語氣,(should )+ 動詞原形.例如： The mad man was put in the soft-padded cell lest he injure himself.（1998年1月四級第38題）
⒌ 在if only 引起的感嘆句中需用虛擬語氣.謂語動詞用過去式或過去完成式.例如： Look at the terrible situation I am in! if only I had followed your advice.
3.用以表示虛擬條件的虛擬語氣
⒈ 用if條件從句表示的虛擬條件,是虛擬條件最普通的方式.
① 虛擬現在時表示與現在事實相反的假設,其if 從句的謂語形式用動詞的過去式(be 一般用were),主句用would/ should/ could/ might +動詞原形,例如：If I were in your position I would marry her.
② 虛擬過去時是表示與過去事實相反的假設,if 從句的謂語形式用過去完成時即had＋過去分詞,主句用would / should / could / might + have +過去分詞,例如：If it had not rained so hard yesterday we could have played tennis.
③ 大多數的虛擬條件句屬於上面三種情況的一種,但並不排除存在條件和後果中,一個和現在情況相反,另一個和過去情況相反,例如：If you had followed what the doctor said, you would not have been so painful now.這個句子在高中出現頻率頗高.
④ 但是,如果後果用了虛擬語氣,而條件卻用陳述語氣,這種用法是錯的.
⒉ 除了表示虛假條件外,if從句還可以表示對將來的推測,由於是將來還沒有發生的,所以談不上是真實的還是虛假的,只能說這個事情發生的可能性有多大.一般情況下,可以用陳述語氣的if從句來表示對一個未來事實的推測,這個事實是完全可能發生的.If從句的謂語形式用一般過去式或用were to / should +動詞原形,主句用would / should /could/ might +動詞原形,例如：Jean doesn"t want to work right away because she thinks that if she were to get a job she probably wouldn"t be able to see her friends very often.（1996年1月四級第44題）
⒊ 有時可以把含有助動詞、情態動詞、be或have的虛擬條件句中的連詞if 省去,而將had , should, were 等詞提到主語之前,即用倒裝結構,這時候,如果出現not等否定詞,否定詞需放在主語後面.這種結構在口語中很少使用,但頻頻出現在各類考試中出現,例如：If it had not rained so hard yesterday we could have played tennis.→Had it not rained so hard yesterday, we could have played tennis.
⒋ 大多數的虛擬條件透過上面所講的兩種方法表達,但在個別句子中也可以透過介詞without和介詞短語but for表達,副詞otherwise等表達出來.例如：We didn"t know his telephone number; otherwise we would have telephoned him.（1995年6月四級第46題）值得注意的是,包含but for的句子,謂語動詞必定要用虛擬形式,但包含without等短語的句子,謂語動詞未必一定要用虛擬語氣.
⒌ 有時虛擬條件不是明確地表達出來,而在蘊含在用but引導的從句裡,於是便出現了有謂語動詞是虛擬語氣的主句加上謂語動詞是陳述語氣的but從句構成的並列複合句,例如I would have hung you but the telephone was out of order.在這樣的句子裡,如果主句沒有用虛擬語氣,或者從句用了虛擬語氣,都是錯的.