My suggestion is that we should go there at once. 我的建議是我們應該馬上去那兒。
4． 省略形式。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，如果出現not等否定詞時需放在主語後面。例如：
If she had been here five minutes earlier she would have seen her old friend. → Had she been here five minutes earlier she would have seen her old friend. 如果她早到五分鐘，她就會看見她的老朋友了。
區別是用法不同。
與過去事實相反的假設。結構為：從句的謂語動詞用“had + 過去分詞”，主句用“should (would, could, might) + have + 過去分詞”。
虛擬語氣用來表示說話人所說的話並不是事實，而是一種假設、願望、懷疑或推測。該語法主要用於if 條件狀語從句中，也可用於主語從句、表語從句和賓語從句等。
虛擬語氣的判斷：
1. if 條件狀語從句中虛擬語氣的判斷。if 條件狀語從句有真實條件句和非真實條件句。假設條件可以實現的句子為真實條件句，反之為非真實條件句，要用虛擬語氣。其形式分為以下三種：
(1) 與過去事實相反的假設。結構為：從句的謂語動詞用“had + 過去分詞”，主句用“should (would, could, might) + have + 過去分詞”。例如：
If it had not rained so hard yesterday, we could have played tennis. 如果昨天沒有下大雨，我們就能玩網球了。
(2) 與現在事實相反的假設。結構為：從句的謂語動詞用過去式，系動詞用were，主句的謂語用“should (would, could, might) + 動詞原形”。例如：
If I were in your position, I would marry her. 如果我是你，我就娶她為妻。
(3) 與將來事實相反的假設。結構為：從句的謂語動詞用“should (were to) + 動詞原形”，主句用“should
(would, could, might) + 動詞原形”。 例如：
If you should miss the chance, you would feel sorry for it. 如果你錯過了這次機會，你會難過的。
2. 賓語從句中的虛擬語氣。
(1) wish後接賓語從句中的虛擬語氣：根據從句的意義來判斷。
A: 表示與現在和將來事實相反的願望，從句謂語動詞用過去時態。例如：
I wish they were not so late. 要是他們來得不是這麼晚就好了。
B: 表示與過去事實相反的願望，從句謂語動詞用過去完成時態。例如：
I wished he hadn"t done that. 我真希望那件事不是他做的。
(2) 表示“要求、建議、命令”等動詞後面的賓語從句中的虛擬語氣。用於此結構的動詞有：advise, direct, agree, ask, demand, decide, desire, insist, order, prefer, propose, request, suggest等。從句的謂語動詞用“should + 動詞原形”，其中should 可以省去。例如：
I insisted that he (should) go with us. 我堅持讓他和我們一起去。
注意：當insist 表示“堅持認為”、suggest表示“表明，顯示”時，不用虛擬語氣。例如：
He insisted that she was honest. 他堅持認為她是誠實的。
3. 主語從句中的虛擬語氣。
(1) It be + 形容詞 + that... (should)...。用於該句型的形容詞有：necessary, good, important, right, wrong, better, natural, proper, funny, strange, surprising等。例如：
It"s natural that he should feel hurt. 他感到疼是很正常的。
(2) It be + 過去分詞 ＋ that... (should)...。用於該結構中的過去分詞是表示“建議、請求、命令”等詞的過去分詞。如： desired, suggested, requested, ordered, proposed等。例如：
It is desired that the building of the house be completed next month. 真希望這所房子在下個月前就能竣工。
(3) It is time (about time / high time) that... + (過去時或should + 動詞原形)...。例如：
It is high time I went home now. = It is high time I should go home. 我該回家了。
(4) 表語從句、同位語從句中的虛擬語氣。在suggestion, proposal, order, plan, idea, advice, decision等需要具體內容解釋的名詞後要使用虛擬語氣，其謂語動詞為：should + 動詞原形，連線從句的that不能省略。例如：
My suggestion is that we should go there at once. 我的建議是我們應該馬上去那兒。
4． 省略形式。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，如果出現not等否定詞時需放在主語後面。例如：
If she had been here five minutes earlier she would have seen her old friend. → Had she been here five minutes earlier she would have seen her old friend. 如果她早到五分鐘，她就會看見她的老朋友了。