虛擬語氣也是一個難點。所謂虛擬語氣是表示說話人的.願望、假設、猜測或建議，而不表示客觀存在的事實。它通過句子的謂語動詞的特殊形式來表示。現歸納如下：純假設，用虛擬，動詞時態退一級：條件句，分主從，主句謂語前加would(should，could，might);表願望，用虛擬，wish後面接賓語(從句)現在過去與將來，動詞時態退一級：提建議，用虛擬，賓語(從句)動詞用(should)do：倆建議，三要求，再加堅持與命令(suggest，advise，demand，require，request，Insist，order)It is time和would rather，後接叢句用虛擬：部分主語從句中，謂語用虛擬結構
(It necessary /important/natural/natural/strange/strange ld do) 下面舉例說明：
you came tomorrow，we would have the meeting.(條件句虛擬)
out air，there would be no living things.(同上)
wish we had arrived there two hours earlier.(表示願望虛擬)
demanded that we(should)start right away.(表示建議虛擬)
is(high)time that we left(should leave)now.(特殊從句虛擬)
F、I would rather you gave me the book.(同上)
G、It is necessary that we should clean the room everyday，(主語從句虛擬)
H、He speaks English so fluently as if he were English.(特殊從句虛擬)